Repositório Institucional - Unifesp :: Navegando por Palavras-chave "Baroreflex"

Navegando por Palavras-chave "Baroreflex"

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Adult spontaneously hypertensive rats from the same laboratory present different baroreflex gain
(Drunpp-sarajevo, 2011-01-01) Valenti, Vitor Engrácia [UNIFESP]; Moura Filho, Oseas Florencio de [UNIFESP]; Abreu, Luiz Carlos de [UNIFESP]; Ferreira, Celso [UNIFESP]; Universidade Federal de São Paulo (UNIFESP); Fac Med ABC
Background: A subset of normotensive Sprague-Dawley rats show lower baroreflex sensitivity; however, no previous study investigated whether there are differences in baroreflex sensitivity within this subset. Thus, we compared baroreflex among adult spontaneously hypertensive rats (SHR).The authors discuss one type of general forward-backward stochastic differential equations (FBSDEs) with It's stochastic delayed equations as the forward equations and anticipated backward stochastic differential equations as the backward equations. The existence and uniqueness results of the general FBSDEs are obtained. In the framework of the general FBSDEs in this paper, the explicit form of the optimal control for linearquadratic stochastic optimal control problem with delay and the Nash equilibrium point for nonzero sum differential games problem with delay are obtained.Results: Approximately 1/10 of rats presented increased bradycardic baroreflex while around 1/5 showed attenuated tachycardic baroreflex. Rats with higher bradycardic baroreflex presented higher basal HR.Conclusion: There is significant alteration regarding baroreflex sensitivity among SHR from the same laboratory.
Acesso aberto (Open Access)
Atividade vasomotora simpática renal e esplâncnica em um modelo de hipertensão por inibição da síntese de óxido nítrico
(Universidade Federal de São Paulo (UNIFESP), 2016-02-29) Zambrano, Lysien Ivania [UNIFESP]; Bergamaschi, Cassia Marta de Toledo [UNIFESP]; http://lattes.cnpq.br/1166526138293050; http://lattes.cnpq.br/9986923610490402; Universidade Federal de São Paulo (UNIFESP)
Systemic hypertension is a multifactorial disease. Among several factors that contributes to the increase in blood pressure, it highlights the deficiency of nitric oxide (NO) and changes in sympathetic vasomotor activity (SNA). The role of NO in the modulation of autonomic function is still controversial in the literature. This work aimed to study the association of sympatoexcitation with inhibition of NO synthesis-induced hypertension. Thus, the present study evaluated the SNA for two different beds, splanchnic and renal (rSNA and sSNA), mean arterial pressure (MAP), heart rate (HR), arterial baroreceptor control for both territories, as well as possible correlations between these parameters and the plasma levels of NO. After eight days of treatment with N-nitro-L-arginine methyl ester (L-NAME - 20mg / kg / day by gavage), a NO sintase inhibitor, obtain 50% increase in MAP, no change in HR, 29% increase in rSNA and 97% sSNA, as well as an increased response to depressing of arterial baroreceptors. Plasma levels of NO were reduced 31% in animals treated with LNAME. Taken altogether, our results demonstrate that inhibition of NO synthesis promotes major hemodynamic changes and autonomic control improvement to different regions innervated by the sympathetic nerves and it is likely that these changes were caused by reduced NO levels both systemically and within brain regions of autonomic control.
Acesso aberto (Open Access)
Baroreflex function in conscious rats submitted to iron overload
(Associação Brasileira de Divulgação Científica, 2005-02-01) Cardoso, Leonardo Máximo; Pedrosa, Maria Lúcia Silva; Silva, Marcelo Eustáquio; Moraes, Márcio Flávio Dutra; Colombari, Eduardo [UNIFESP]; Chianca-Junior, Deoclécio Alves; Universidade Federal de Ouro Preto NUPEB Departamento de Ciências Biológicas; Universidade Federal de Ouro Preto Escola de Nutrição Departamento de Alimentos; Universidade Federal de Minas Gerais Instituto de Ciências Biológicas Departamento de Fisiologia e Biofísica; Universidade Federal de São Paulo (UNIFESP)
Our hypothesis is that iron accumulated in tissue, rather than in serum, may compromise cardiovascular control. Male Fischer 344 rats weighing 180 to 220 g were divided into 2 groups. In the serum iron overload group (SIO, N = 12), 20 mg elemental iron was injected ip daily for 7 days. In the tissue iron overload group (TIO, N = 19), a smaller amount of elemental iron was injected (10 mg, daily) for 5 days followed by a resting period of 7 days. Reflex heart rate responses were elicited by iv injections of either phenylephrine (0.5 to 5.0 µg/kg) or sodium nitroprusside (1.0 to 10.0 µg/kg). Baroreflex curves were determined and fitted to sigmoidal equations and the baroreflex gain coefficient was evaluated. To evaluate the role of other than a direct effect of iron on tissue, acute treatment with the iron chelator deferoxamine (20 mg/kg, iv) was performed on the TIO group and the baroreflex was re-evaluated. At the end of the experiments, evaluation of iron levels in serum confirmed a pronounced overload for the SIO group (30-fold), in contrast to the TIO group (2-fold). Tissue levels of iron, however, were higher in the TIO group. The SIO protocol did not produce significant alterations in the baroreflex curve response, while the TIO protocol produced a nearly 2-fold increase in baroreflex gain (-4.34 ± 0.74 and -7.93 ± 1.08 bpm/mmHg, respectively). The TIO protocol animals treated with deferoxamine returned to sham levels of baroreflex gain (-3.7 ± 0.3 sham vs -3.6 ± 0.2 bpm/mmHg) 30 min after the injection. Our results indicate an effect of tissue iron overload on the enhancement of baroreflex sensitivity.
Somente Metadadados
Baroreflex Sensitivity Impairment Is Associated With Cardiac Diastolic Dysfunction in Rats
(Churchill Livingstone Inc Medical Publishers, 2011-06-01) Mostarda, Cristiano; Moraes-Silva, Ivana Cinthya; Moreira, Edson Dias; Medeiros, Alessandra [UNIFESP]; Piratello, Aline Cristina; Consolim-Colombo, Fernanda Marciano; Caldini, Elia Garcia; Brum, Patricia Chakur; Krieger, Eduardo Moacyr; Irigoyen, Maria Claudia; Universidade de São Paulo (USP); Universidade Federal de São Paulo (UNIFESP)
Background: Studies have shown that the autonomic dysfunction accompanied by impaired baroreflex sensitivity was associated with higher mortality. However, the influence of decreased baroreflex sensitivity on cardiac function, especially in diastolic function, is not well understood. This study evaluated the morpho-functional changes associated with baroreflex impairment induced by chronic sinoaortic denervation (SAD).Methods and Results: Animals were divided into sinoaortic denervation (SAD) and control (C) groups. Baroreflex sensitivity was evaluated by tachycardic and bradycardic responses, induced by vasoactive drugs. Cardiac function was studied by echocardiography and by left ventricle (LV) catheterization. LV collagen content and the expression of regulatory proteins involved in intracellular Ca(2+) homeostasis were quantified. Results showed higher LV mass in SAD versus C animals. Furthermore, an increase in deceleration time of E-wave in the SAD versus the C group (2.14 +/- 0.07 ms vs 1.78 +/- 0.03 ms) was observed. LV end-diastolic pressure was increased and the minimum dP/dt was decreased in the SAD versus the C group (12 +/- 1.5 mm Hg vs 5.3 +/- 0.2 mm Hg and 7,422 +/- 201 vs 4,999 +/- 345 mm Hg/s, respectively). SERCA/NCX ratio was lower in SAD than in control rats. the same was verified in SERCA/PLB ratio.Conclusions: the results suggest that baroreflex dysfunction is associated with cardiac diastolic dysfunction independently of the presence of other risk factors. (J Cardiac Fail 2011;17:519-525)
Somente Metadadados
Bradykinin microinjection in the paratrigeminal nucleus triggers neuronal discharge in the rat rostroventrolateral reticular nucleus
(Natl Research Council Canada, 2004-07-01) Caous, Cristofer André [UNIFESP]; Balan, Antonio Claudir [UNIFESP]; Lindsey, Charles Julian [UNIFESP]; Universidade Federal de São Paulo (UNIFESP)
A small collection of neurons in the dorsal lateral medulla, the paratrigeminal nucleus (Pa5), projects directly to the rostroventrolateral reticular nucleus (RVL). Bradykinin (BK) microinjections in the Pa5 produce marked pressor responses. Also, the Pa5 is believed to be a component of the neuronal substrates of the somatosensory response and the baroreflex arc. Considering the developing interest in the functional physiology of the Pa5, the present study was designed to characterize RVL neuronal activity in response to BK microinjections in the Pa5 as well as to phenylephrine-induced blood pressure increases in freely behaving rats. of the 46 discriminated RVL neurons, 82% responded with a 180% mean increase in firing rate after BK application to the paratrigeminal nucleus, before the onset of the blood pressure increase. Thirty (79%) of the RVL BK-excited neurons were baroreceptor-inhibited units that responded with a 30% decrease in firing rate in response to a phenylephrine-produced increase of blood pressure. Twenty-seven (71%) units of the latter population displayed cardiac-cycle-locked rhythmic activity. the findings demonstrate a BK-stimulated functional connection between the Pa5 and RVL that may represent the neural pathway in the BK-mediated pressor response. This pathway may be relevant to baroreflex mechanisms since it relates to cardiovascular pressure-sensitive neurons.
Acesso aberto (Open Access)
Caracterização dos efeitos da exposição aos componentes do cigarro sobre o controle neural do sistema cardiovascular em ratos normotensos e ratos espontaneamente hipertensos
(Universidade Federal de São Paulo (UNIFESP), 2011-06-29) Valenti, Vitor Engrácia [UNIFESP]; Ferreira, Celso [UNIFESP]; Universidade Federal de São Paulo (UNIFESP)
Objectives: To evaluate the effects of sidestream cigarette smoke (SSCS) on neural control of cardiovascular system in normotensive and spontaneously hypertensive rats (SHR). Method: Wistar, Wistar-Kyoto rats (WKY) and SHR were exposed to SSCS for three weeks, five days per week, 180 minutes per day at a concentration of carbon monoxide between 100 and 300 ppm. Baroreflex was stimulated with a vasodepressor dose of sodium nitroprusside (NPNa, 50ìg/kg, iv) and with a pressor dose of phenylephrine (PE, 8ìg/kg, iv). In order to evaluate the effects of catalase inhibition into the fourth cerebral ventricle (4th V) on cardiovascular responses, we injected the catalase inhibitor 3-amino-1,2,4-triazole (ATZ, ìg/100ìL 0.01). Results: It was observed in Wistar rats exposed to SSCS that catalase inhibition caused more intense responses on basal HR and bradycardic peak. Central catalase inhibition affected in a higher intensity baseline HR and bradycardic peak WKY rats exposed to SSCS. On the other hand, in SHR SSCS exposure affected the tachycardic peak after central inhibition of catalase in a higher intensuty. Conclusion: Exposure to SSCS alters the sympathetic component of the baroreflex in WKY and SHR and caused more severe cardiovascular responses to catalase inhibition into the 4th V in Wistar and WKY rats.
Somente Metadadados
Cardiovascular and baroreceptor functions of the paratrigeminal nucleus for pressor effects in non-anaesthetized rats
(Elsevier B.V., 2009-05-11) Sousa, L. O. [UNIFESP]; Lindsey, Charles Julian [UNIFESP]; Universidade Federal de São Paulo (UNIFESP)
Located in the lower brainstem, the paratrigeminal nucleus (Pa5) is related to cardiorespiratory autonomic reflex functions. To characterize the structures' role in blood pressure regulation and baroreflex response, both resting cardiovascular parameters and reflex responses were evaluated during phenylephrine-produced pressor responses in non-anaesthetized rats with or without bilateral chemical Pa5 ablation. the Pa5-ablated animals, in contrast to the Pa5-intact control animals, presented increased resting arterial pressure (115 +/- 4 vs. 100 +/- 3 mm, Hg), decreased heart (293 +/- 10 vs. 315 +/- 7 bpm) and increase of the respiratory (104 3 vs. 94 5 rpm) rates, larger pressor responses and reduced baroreflex index (1.6 +/- 02 vs. 2.8 +/- 0.2, p < 0.05). the cardiovascular changes, compatible to those produced by nucleus of the solitary tract (NTS) lesions in non-anaesthetized rats, indicate a reduction of both the sympathetic and cardiac components of the baroreflex response. Further analyses showed the Pa5 mediates reflex responses to smaller blood pressure increases, while the NTS would be predominantly active in surges over 40 mm Hg. Thus, the integrity of the Pa5 is important for resting blood pressure maintenance as for a full baroreceptor response. (c) 2008 Elsevier B.V. All rights reserved.
Somente Metadadados
Cardiovascular autonomic dysfunction in non-obese diabetic mice
(Elsevier B.V., 2013-10-01) Moraes, Oscar A.; Colucci, Juliana A. [UNIFESP]; Souza, Leandro E.; Scapini, Katia B.; Moraes-Silva, Ivana C.; Mostarda, Cristiano; De Angelis, Katia; Casarini, Dulce E. [UNIFESP]; Irigoyen, Maria Claudia; Universidade de São Paulo (USP); Nove de Julho Univ; Universidade Federal de São Paulo (UNIFESP); Univ Fed Maranhao
It is known that diabetes is associated with autonomic dysfunction; however, data about autonomic function in non-obese diabetic mice (NOD) remain scarce. We evaluated the autonomic profile of NOD mice. Female mice, 24-28 week old, were divided in two groups: NOD (n = 6) and control (n = 6, Swiss mice). NOD mice with glycemia >= 300 mg/dl were used. Heart rate variability (HRV) and arterial pressure variability (APV) in time and frequency domains, symbolic analysis of heart rate (HR) and baroreflex sensitivity were evaluated. HR and arterial pressure (AP) were similar between the groups; however, HRV (total variance of RR interval: NOD = 21.07 +/- 3.75 vs. C = 42.02 +/- 6.54 ms(2)) and the vagal modulation index RMSSD were lower in NOD group (4.01 +/- 032 vs. 8.28 +/- 0.97 ms). Moreover, the absolute and normalized low-frequency (LF) components were also enhanced in NOD (normalized = 61.0 +/- 4.0%) as compared to control mice (normalized = 20.0 +/- 4.0%). Both the absolute and normalized high-frequency (HF) components were lower in NOD (normalized = 39.0 +/- 4.0%) when compared to the control group (normalized = 80.0 +/- 4.0). in the symbolic analysis the 0V pattern, an indication of sympathetic activity, was higher in NOD and 2LV pattern, an indication of parasympathetic activity, was lower in the NOD than in the control group. Both bradycardic and tachycardic responses were decreased in NOD (3.01 +/- 0.72 vs. 4.54 +/- 0.36 bpm/mm Hg and 2.49 +/- 031 vs. C = 3.43 +/- 033 bpm/mm Hg) when compared to the control group. Correlation analysis showed negative correlations between vagal indexes (RMSSD, %HF and 2LV) and glycemic levels. in conclusion, NOD mice develop severe diabetes correlated with autonomic dysfunction. (C) 2013 Elsevier B.V. All rights reserved.
Acesso aberto (Open Access)
Cardiovascular control in experimental diabetes
(Associação Brasileira de Divulgação Científica, 2002-09-01) De Angelis, Katia; Schaan, Beatriz D'Agord; Maeda, C.y.; Dal Lago, Pedro; Wichi, Rogerio Brandao [UNIFESP]; Irigoyen, Maria Claudia [UNIFESP]; Universidade de Santo Amaro UNIPESQ Laboratório de Cardiovascular; Universidade Federal do Rio Grande do Sul Instituto de Ciências Básicas da Saúde Departamento de Fisiologia; Instituto de Cardiologia do Rio Grande do Sul Fundação Universitária de Cardiologia; Universidade Federal de São Paulo (UNIFESP); Universidade de São Paulo (USP); Pontifícia Universidade Católica do Rio Grande do Sul FAENFI Curso de Fisioterapia
Several studies have reported impairment in cardiovascular function and control in diabetes. The studies cited in this review were carried out from a few days up to 3 months after streptozotocin administration and were concerned with the control of the circulation. We observed that early changes (5 days) in blood pressure control by different peripheral receptors were maintained for several months. Moreover, the impairment of reflex responses observed after baroreceptor and chemoreceptor stimulation was probably related to changes in the efferent limb of the reflex arc (sympathetic and parasympathetic), but changes also in the central nervous system could not be excluded. Changes in renal sympathetic nerve activity during volume expansion were blunted in streptozotocin-treated rats, indicating an adaptive natriuretic and diuretic response in the diabetic state. The improvement of diabetic cardiovascular dysfunction induced by exercise training seems to be related to changes in the autonomic nervous system. Complementary studies about the complex interaction between circulation control systems are clearly needed to adequately address the management of pathophysiological changes associated with diabetes.
Somente Metadadados
CATALASE INHIBITION INTO the FOURTH CEREBRAL VENTRICLE AFFECTS BRADYCARDIC PARASYMPATHETIC RESPONSE TO INCREASE in ARTERIAL PRESSURE WITHOUT CHANGING the BAROREFLEX
(Imperial College Press, 2011-03-01) Valenti, Vitor E. [UNIFESP]; De Abreu, Luiz Carlos; Sato, Monica A.; Fonseca, Fernando L. A.; Perez Riera, Andres R.; Ferreira, Celso [UNIFESP]; Universidade Federal de São Paulo (UNIFESP); Fac Med ABC
Exogenous catalase influences neural control of cardiovascular system; however, we do not know yet if its inhibition into the fourth cerebral ventricle (4(th) V) influences baroreflex regulation. We evaluated the effects of central catalase inhibition on baroreflex in conscious Wistar rats. We used males Wistar rats (320-370 g), which were implanted with a stainless steel guide cannula into 4(th) V. the femoral artery and vein were cannulated for mean arterial pressure (MAP) and heart rate (HR) measurement and drug infusion, respectively. After basal MAP and HR recordings, the baroreflex was tested with a pressor dose of phenylephrine (PHE, 8 mu g/kg, bolus) and a depressor dose of sodium nitroprusside (SNP, 50 mu g/kg, bolus). Baroreflex was evaluated before 5, 15, 30 and 60 minutes after 3-amino1,2,4- triazole (ATZ, 0.001 g/100 mu L) injection into the 4(th) V. Vehicle treatment did not change baroreflex responses. ATZ attenuated bradycardic peak and reduced HR range at 30 minutes. ATZ into the 4(th) V reduced bradycardic and tachycardic reflex responses to increase and decrease MAP, respectively (p < 0.05) 30 minutes after its microinjection without significantly changing the basal MAP and HR. in conclusion, central catalase inhibition influenced the highest parasympathetic response to MAP increase in conscious Wistar rats without change baroreflex gain.
Somente Metadadados
CENTRAL N-ACETYLCYSTEINE EFFECTS ON BAROREFLEX in JUVENILE SPONTANEOUSLY HYPERTENSIVE RATS
(Imperial College Press, 2011-06-01) Valenti, Vitor E. [UNIFESP]; De Abreu, Luiz Carlos; Sato, Monica A.; Saldiva, Paulo H. N.; Fonseca, Fernando L. A.; Giannocco, Gisele; Riera, Andreas R. P.; Ferreira, Celso [UNIFESP]; Universidade Federal de São Paulo (UNIFESP); Universidade de São Paulo (USP)
In this study, we evaluated the acute effects of central NAC administration on baroreflex in juvenile SHR and Wistar Kyoto (WKY) rats. Male SHR and WKY rats (8 10 weeks old) were implanted with a stainless steel guide cannula into the fourth cerebral ventricle (4th V). the femoral artery and vein were cannulated for mean arterial pressure (MAP) and heart rate (HR) measurement and drug infusion, respectively. After basal MAP and HR recordings, the baroreflex was tested with a pressor dose of phenylephrine (PHE, 8 mu g/kg, bolus) and a depressor dose of sodium nitroprusside (SNP, 50 mu g/kg, bolus). Baroreflex was evaluated before, 5, 15, 30 and 60 minutes after NAC injection into the 4th V. Vehicle treatment did not change baroreflex responses in WKY and SHR. Central NAC slightly but significantly increased basal HR at 15 minutes and significantly reduced PHE-induced increase in MAP 30 and 60 minutes after NAC injection (p < 0.05) in WKY rats. in relation to SHR, NAC decreased HR range 15 and 30 minutes after its administration. in conclusion, acute NAC into the 4th V does not improve baroreflex in juvenile SHR.
Somente Metadadados
Change in central kinin B2 receptor density after exercise training in rats
(Elsevier B.V., 2010-12-08) Caetano, Ariadiny Lima; Viel, Tania Araujo; Queiroz Prado Bittencourt, Maria Fernanda; Araujo, Mariana Silva [UNIFESP]; De Angelis, Katia; Buck, Hudson Sousa; Fac Ciencias Med Santa Casa São Paulo; Universidade de São Paulo (USP); Universidade Federal de São Paulo (UNIFESP); Univ Sao Judas Tadeu
Cardiovascular responses elicited by the stimulation of kinin B2 receptors in the IV cerebral ventricle paratrigeminal nucleus or in the thoracic spinal cord are similar to those observed during an exercise bout Considering that the kalikrein-kinin system (KKS) could act on the cardiovascular modulation during behavioral responses as physical exercise or stress this study evaluated the central B2 receptor densities of Wistar (W) and spontani ously hypertensive rats (SHR) after chronic moderate exercise Animals we re exercise-trained for ten weeks on a treadmill Afterwards systolic blood pressure decreased in both trained strains Animals were killed and the medulla and spinal cord extracted for B2 receptor autoradiography Trained animals were compared to their sedentary controls Sedentary groups showed specific binding sites for Hoe-140 (fmol/mg of tissue) in laminas 1 and 2 of the spinal cord nucleus of the solitary tract (NTS) area postrema (AP) spinal trigeminal tract (sp5) and paratrigeminal nucleus (Pa5) in trained W a significant increase (p<0 05) in specific binding was observed in the Pa5 (31 3%) and NTS (28 2%) Trained SHR showed a significant decrease in n ceptor density in lamina 2 (21 9%) of the thoracic spinal cord and an increase in specific binding in Pa5 (36 1%) We suggest that in the medulla chronic exercise could hyper stimulate the KKS enhancing their efficiency through the increase of B2 receptor density involving this receptor in central cardiovascular control during exercise or stress in the lamina 2 B2 receptor might be involved in the exercise-induced hypotension (C) 2010 Elsevier BV All rights reserved
Acesso aberto (Open Access)
Efeito do treinamento resistido na sensibilidade barorreflexa de ratos SHR
(Universidade Federal de São Paulo (UNIFESP), 2013-12-17) Borges, Mariana Eiras [UNIFESP]; Medeiros, Alessandra [UNIFESP]; http://lattes.cnpq.br/0071198026371230; http://lattes.cnpq.br/2967870697533392; Universidade Federal de São Paulo (UNIFESP)
Os barorreceptores atuam como reguladores da pressão arterial, sendo sensíveis a modificações na parede dos vasos, conseguem gerar potenciais de ação no sistema nervoso central. A sensibilidade dos barorreceptores pode diminuir em pessoas hipertensas e o treinamento físico pode fazer com que isso não aconteça ou que a sensibilidade volte ao seu normal. Estudos já comprovam essa capacidade quando o treinamento físico é do tipo aeróbio, porém, o efeito do treinamento físico resistido na sensibilidade dos barorreceptores ainda não é conhecido. Ademais, a efetividade do treinamento físico resistido para o tratamento de indivíduos hipertensos ainda é controversa na literatura. No entanto, esse tipo de treinamento é de extrema importância, já que pode promover aumento de força e massa muscular, prevenindo a sarcopenia no idoso. Portanto, o objetivo do presente trabalho foi avaliar a sensibilidade barorreflexa em ratos espontaneamente hipertenso (SHR) submetidos a um programa de treinamento físico resistido. Para isso, foram utilizados ratos Wistar (grupo controle) e SHR, divididos em quatro grupos: Wistar sedentário (CS), Wistar treinado (CT), SHR sedentário (HS) e SHR treinado (HT). Os animais treinados foram submetidos a um protocolo de treinamento físico resistido em escada, por 8 semanas, cinco vezes por semana. Durante todo o período experimental a pressão arterial e frequência cardíaca foram acompanhadas um vez por semana, por meio de medida indireta. Após o período experimental, os animais foram submetidos à cateterização artério-venosa com o objetivo de obter um registro direto de pressão arterial pulsátil e frequência cardíaca. O controle barorreflexo da frequência cardíaca foi avaliado através das respostas de bradicardia frente a um estímulo pressor e de taquicardia após um estímulo depressor. Após o período de treinamento físico verificou-se melhora da resposta bradicárdica no grupo HT, porém não houve diminuição da pressão arterial no mesmo grupo, e em relação a frequência cardíaca não foi encontrada diferença significativa
Embargo
Efeito do Treinamento Físico no Perfil Hemodinâmico de Ratas Diabéticas Ooforectomizadas
(Universidade Federal de São Paulo (UNIFESP), 2006-12-31) Souza, Silvia Beatriz Paulino Cavasin de [UNIFESP]; Irigoyen, Maria Claudia [UNIFESP]; Universidade Federal de São Paulo (UNIFESP)
Diabetes and menopause markedly increase the risk of cardiovascular disease among women. The objective of the present study was to investigate the effects of exercise training on cardiovascular autonomic dysfunction and in the incidence of mortality in diabetic female rats submitted to ovarian hormones deprivation. Female Wistar rats were divided in ovariectomized groups: sedentary and trained (SO) controls (TO), and sedentary (SDO) and trained diabetics (TDO). Diabetes was induced by a single streptozotocin injection (50 mg/kg i.v.) 15 days after ovariectomy. Arterial pressure (AP), heart rate (HR), heart rate variability (HRV), baroreflex sensitivity and autonomic control of HR were evaluated after the exercise training period on treadmill, started 1 week after ovariectiomy. SO group presented highest body weight at the end of the protocol (346±7g) and also highest mean AP (124±3 mmHg) and HR (361±13 bpm) in relation to other studied groups. OT group showed reduced body weight (325±7g), mean AP (113±2 mmHg) and HR (327±5 bpm) as compared to OS group. DSO animals presented reduced body weight (186±7g), bradycardia (251±8 bpm) and hypotension (102±2 mmHg) when compared to OS animals. TDO rats showed attenuation of these alterations. Diabetes impaired baroreflex sensitivity (~55%). Exercise training induced an improvement in bradycardic and tachycardic responses in controls (~40 and 74%) and diabetic (~89 and 74%) groups in relation to their respective sedentary groups. Heart rate variability was reduced in sedentary diabetic rats (13±1.3 bpm) when compared to sedentary rats (18±1.5 bpm). Trained groups showed an increase in heart rate variability (23±1 and 21±1.2 bpm in trained diabetic group) as compared with sedentary groups. Diabetes reduced vagal tonus (~68%). Trained diabetic group presented similar vagal tonus than sedentary control and reduced sympathetic tonus when compared to others studied groups. IHR was reduced in SDO rats in relation to SO rats and exercise training attenuated this dysfunction. Correlation analysis showed a relationship between heart rate variability and vagal tonus with bradycardic (r=-0.5 and r=-0.5) and with tachycardic (r=0.6 and r=0.6) responses to AP changes. Mortality was 50% and 25 % among sedentary and trained diabetic animals, respectively. Together these findings may provide insight that baroreflex sensitivity and heart rate variability impairments are potential mechanisms responsible for the enhanced CVD-related mortality observed in diabetic women, as well as, that exercise training-induced autonomic improvement can lower the incidence of mortality in diabetic postmenopause women.
Acesso aberto (Open Access)
Efeitos cardiovasculares ao tratamento crônico com vitamina C na hipertensão renovascular em ratos Wistar
(Universidade Federal de São Paulo (UNIFESP), 2010-01-27) Nishi, Erika Emy [UNIFESP]; Campos, Ruy Ribeiro [UNIFESP]; Universidade Federal de São Paulo (UNIFESP)
Sympathetic vasomotor hyperactivity and baroreflex dysfunction are involved in the development and maintenance of Goldblatt 2 kidney, 1 clip (2K-1C) model of renovascular arterial hypertension (AH). This experimental model of AH is reninangiotensin system activation-dependent and the interaction of angiotensin (Ang) II with its subtype 1 receptor (AT1) activates the NAD(P)H oxidases enzymes, increasing superoxide anion production. We hypothesized that oxidative stress contributes to cardiovascular dysfunctions in the 2K-1C model. The aim of the present study was to evaluate the effects of chronic administration of an antioxidant, vitamin C (Vit C - 150 mg/kg/day) on mean arterial pressure (MAP), baroreceptor reflex (BR) and renal sympathetic nerve activity (rSNA) in male Wistar 2K-1C rats. Comparatively, the same cardiovascular parameters were evaluated under the effect of chronic treatment with AT1R blocker, losartan (Los - 30 mg/kg/day). Moreover, gene expressions (messenger RNA) of AT1, NAD(P)H oxidase subunits (p47phox and gp91phox) and the main antioxidant enzymes: superoxide dismutase (SOD), catalase (CAT) and glutathione peroxidase (GPx) were evaluated in the renal cortex as renal oxidative stress markers. Vit C treatment decreased basal MAP and rSNA only in the hypertensive group, increased cardiac BR gain to the bradycardic response (vagal component) and improved renal BR sensibility in control and 2K-1C groups, more intensely in hypertensive group. Addionally, Vit C decreased AT1 gene expression only in the clipped kidney and augmented GPx expression in both kidneys of hypertensive group. Los treatment normalized PAM and rSNA and increased cardiac BR to the bradycardic response only in the hypertensive group and improved renal BR more intensely in 2K-1C group. Therefore, the present study showed that chronic Vit C treatment improved hypertension and the control of baroreceptor reflex to the heart and the rSNA associated with reduced gene expression of AT1 and increased GPx expression in the ischemc kidney. Taken altogether, these data suggest a role for oxidative stress and rSNA in the maintenance of Ang II-dependent AH.
Acesso aberto (Open Access)
The Effect of Physical Resistance Training on Baroreflex Sensitivity of Hypertensive Rats
(Arquivos Brasileiros Cardiologia, 2017) Gomes, Moisés Felipe Pereira [UNIFESP]; Borges, Mariana Eiras [UNIFESP]; Rossi, Vitor de Almeida [UNIFESP]; Moura, Elizabeth de Orleans Carvalho de [UNIFESP]; Medeiros, Alessandra [UNIFESP]; Universidade Federal de São Paulo (UNIFESP)
Background: Baroreceptors act as regulators of blood pressure (BP); however, its sensitivity is impaired in hypertensive patients. Among the recommendations for BP reduction, exercise training has become an important adjuvant therapy in this population. However, there are many doubts about the effects of resistance exercise training in this population. Objective: To evaluate the effect of resistance exercise training on BP and baroreceptor sensitivity in spontaneously hypertensive rats (SHR). Method: Rats SHR (n = 16) and Wistar (n = 16) at 8 weeks of age, at the beginning of the experiment, were randomly divided into 4 groups: sedentary control (CS, n = 8); trained control (CT, n = 8); sedentary SHR (HS, n = 8) and trained SHR (HT, n = 8). Resistance exercise training was performed in a stairmaster-type equipment (1.1 × 0.18 m, 2 cm between the steps, 80° incline) with weights attached to their tails, (5 days/week, 8 weeks). Baroreceptor reflex control of heart rate (HR) was tested by loading/unloading of baroreceptors with phenylephrine and sodium nitroprusside. Results: Resistance exercise training increased the soleus muscle mass in SHR when compared to HS (HS 0.027 ± 0.002 g/mm and HT 0.056 ± 0.003 g/mm). Resistance exercise training did not alter BP. On the other hand, in relation to baroreflex sensitivity, bradycardic response was improved in the TH group when compared to HS (HS –1.3 ± 0.1 bpm/mmHg and HT –2.6 ± 0.2 bpm/mmHg) although tachycardia response was not altered by resistance exercise (CS –3.3 ± 0.2 bpm/mmHg, CT –3.3 ± 0.1 bpm/mmHg, HS –1.47 ± 0.06 bpm/mmHg and HT –1.6 ± 0.1 bpm/mmHg). Conclusion: Resistance exercise training was able to promote improvements on baroreflex sensitivity of SHR rats, through the improvement of bradycardic response, despite not having reduced BP. (Arq Bras Cardiol. 2017; 108(6):539-545)
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Função do núcleo paratrigeminal na homeostase circulatória e reflexos cardiorrespiratórios
(Universidade Federal de São Paulo (UNIFESP), 2010-03-31) Sousa, Luana de Oliveira [UNIFESP]; Lindsey, Charles Julian [UNIFESP]; Universidade Federal de São Paulo (UNIFESP)
Recentes investigações inserem 0 núcleo paratrigeminal entre 0 grupo de estruturas bulbares relacionadas ao controle homeostático. Para compreender sua participação nestes mecanismos avaliamos 0 efeito da lesão neuroquímica do núcleo, ou de suas sub-regiões, na resposta reflexa a estímulos pressores e depressores durante diferentes períodos pós ablação da estrutura. Também avaliamos 0 atividade elétrica neuronal através de registro simultâneo de muitos neurônios ou "multi-chonnel ensemble recording” durante alterações da pressão arterial. Os resultados mostraram que a integridade do núcleo é fundamental para a manutenção da pressão arterial de repouso como também para os componentes de compensação cardíaca e de tamponamento do simpático-vascular barorreflexos aos aumentos ou diminuições da pressão arterial. Aparentemente 0 núcleo parotrigeminal atuaria em tamponar pequenos e médios alterações da pressão arterial, dentro da faixa de oscilações das batidas cardíacas (40 mmHg em ratos), enquanto que 0 núcleo do trato solitário (NTS) atuaria tamponando as maiores alterações da pressão, sugerindo que as estruturas atuem com funções complementares. Lesões seletivas do núcleo paratrigeminal ossociaram a porção caudal à função barorreflexa e a porção interpolar e rostral na manutenção do tônus vascular e ou simpático. Uma estreito coluna de neurônios no aspecto lateral da região interpolar/caudal do núcleo teria importância fundamental para a manutenção do tônus vascular e pressão arterial de repouso. 0 decurso temporal dos efeitos da lesão do núcleo evidência a adaptação e plasticidade das redes neurais levando 0 uma reorganização para substituir funcionalmente a estrutura danificado. 0 registro simultâneo de neurônios paratrigeminais mostrou uma atividade elétrica compatível ao esperado de neurônios sensíveis à estimulação pressoceptora, observados no NTS. Evidência de recrutamento neuronal ocorre durante a fase ascendente da resposta pressora e a redução no número de neurônios que aumentaram a atividade elétrica no pico do efeito pressor pode refletir a cessação do efeito do recrutamento, possivelmente como parte do processo de resetting de curto prazo dos barorreceptores. Também, 0 número de neurônios que diminuíram ou aumentaram a taxa de disparo durante os eventos pressores e depressores pode representar a desativação ou ativação quimioreceptora, em resposta ao aumento ou queda do pressão arterial, respectivamente. Similar ao NTS, aproximadamente 90% dos neurônios paratrigeminois apresentaram atividade rítmico atrelada ao ciclo cardíaco, a maioria com múltiplos picos com distintas frequências, e grande proporção de neurônios com atividades rítmicas altamente sincronizadas com 0 rítmo respiratório ou outros. A assimetria e a falta de coerêncio da atividade dos neurônios frente a alterações opostas da pressão arterial, os múltiplos picos associados a atividade rítmicas sugere que 0 núcleo, além das aferências bororreceptoras receba também aferências convergentes, excitatórias e inibitórias, de origem quimioreceptora, cardiopulmonar, somatosensorial e ou nociceptiva. As informações convergentes ao núcleo seriam processadas 'por redes neurais e repassadas às outras estruturas bulbares relacionadas à homeostase cordiovascular e respiratória. Os dados apontam homologias entre o núcleo paratrigeminal e 0 NTS e, do ponto de vista evolutivo, o núcleo paratrigeminal poderia ser uma diferenciação funcional do NTS, próprio para fornecer ajustes finos e rápidos requeridos nos animais homeotermos..
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Important GABAergic mechanism within the NTS and the control of sympathetic baroreflex in SHR
(Elsevier B.V., 2011-01-20) Moreira, Thiago S.; Takakura, Ana C.; Colombari, Eduardo [UNIFESP]; Universidade de São Paulo (USP); São Paulo State Univ UNESP; Universidade Federal de São Paulo (UNIFESP)
Inhibitory neurotransmission has an important role in the processing of sensory afferent signals in the nucleus of the solitary tract (NTS), particularly in spontaneously hypertensive rats (SHR). in the present study, we tested the hypothesis that gamma-aminobutyric acid (GABA) mediated neurotransmission within the NTS produces an inhibition of the baroreflex response of splanchnic sympathetic nerve discharge (sSND). in urethane-anesthetized, artificially ventilated and vagotomized male SHR and Wistar Kyoto (WKY) rats we compared baroreflex-response curves evoked after bilateral injections into the NTS of the GABA-A antagonist bicuculline (25 pmol/50 nl) or the GABA-B antagonist CGP 35348 (5 nmol/50 nl). Baseline MAP in SHR was higher than the WKY rats (SHR: 153+/-5, vs. WKY: 112+/-6 mm Hg, p<0.05). Bilateral injection of bicuculline or CGP 35348 into the NTS induced a transient (5 min) reduction in MAP (Delta = -26+/-4 and -41+/-6 mm Hg, respectively vs. saline Delta = +4+/-3 mm Hg, p<0.05) and sSND (Delta = -21+/-13 and -78+/-7%, respectively vs. saline: Delta = +6+/-4% p<0.05). Analysis of the baroreceptor curve revealed a decrease in the lower plateau (43+/-11 and 15+/-5%, respectively vs. saline: 78+/-6%, p<0.05) and an increase in the sympathetic gain of baroreflex (6.3+/-0.3, 7.2+/-0.8% respectively vs. saline: 4.2+/-0.4%, p<0.05). Bicuculline or CGP35348 into the NTS in WKY rats did not change MAP, sSND and sympathetic baroreflex gain. These data indicate that GABAergic mechanisms within the NTS act tonically reducing sympathetic baroreflex gain in SHR. Crown Copyright (C) 2010 Published by Elsevier By. All rights reserved.
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Neuronal connections of the paratrigeminal nucleus: a topographic analysis of neurons projecting to bulbar, pontine and thalamic nuclei related to cardiovascular, respiratory and sensory functions
(Elsevier B.V., 2001-12-10) Caous, Cristofer André [UNIFESP]; Buck, Hudson de Sousa [UNIFESP]; Lindsey, Charles Julian [UNIFESP]; Universidade Federal de São Paulo (UNIFESP)
The paratrigeminal nucleus, which receives sensory input from trigeminal, glossopharyngeal and vagus nerves, has efferent projections to bulbar. pontine and possibly to thalamic structures associated with nociception, thermoregulation and cardiovascular control. Anterograde neuronal tracers were used to study paratrigeminal efferent connections. Labeled terminal fibers. evidencing bilateral efferent paratrigeminal projections were observed in the medial and caudal solitary tract (sot), lateral reticular nucleus (LRt). ambiguus nucleus (Amb). rostroventrolateral reticular nucleus (RVL). while ipsilateral projections were found in the parabrachial (PB) nuclei and ventral portion of the ventral posteromedial thalamic nucleus (VPM). This extends other findings that describe paratrigeminal projections. Retrograde neuronal transport tracers, microinjected in the defined projection areas were used to map distribution of the paratrigeminal neurons originating different efferent connections. Microinjection of latex microspheres containing fluorescein or rhodamine and Fluoro-gold in the ventral VPM. PB, RVL, Amb, LRt and NTS revealed sets of labeled paratrigeminal nucleus neurons respectively organised in a rostral-caudal sequence. the largest extent of the paratrigeminal nucleus (medial portion) contained neurons projecting to the RVL/Amb. structures associated with cardiovascular regulation. the data show a segmented topographical organization of the nucleus. with different sets of neurons within delimited segments, projecting to neuronal structures associated with different functions. This points to a complex and extensive role for the paratrigeminal nucleus in the integration of somatosensory reflexes related to cardiovascular. respiratory and pain mechanisms. the nucleus may act as a medullary relay interposed between sensory afferents and different structures related to homoeostatic functions.
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Papel do sistema nervoso autônomo no risco cardiovascular em pacientes com Litíase Renal
(Universidade Federal de São Paulo (UNIFESP), 2020-01-30) Zambrano, Lysien Ivania [UNIFESP]; Bergamaschi, Cassia Marta De Toledo [UNIFESP]; Universidade Federal de São Paulo
Introduction: Kidney stone (KS) is a highly prevalent disease worldwide. Studies indicate that there is a direct correlation between the presence of KS and CVD and that individuals with KS are more likely to develop hypertension compared to individuals without KS. Aim: To investigate the possible role of the autonomic nervous system (ANS) in cardiovascular risk (CVR) of patients with kidney stone. Patients and Methods: We included in the KS group 19 patients of both sexes aged 18-60 years and diagnosed with KS. The control group (CTL) was composed of 21 individuals without diagnosis of KS. MAP, SBP, DBP and HR at rest and in response to cardiovascular challenges in orthostatism, modified orthostatism, Cold Pressor test (CPT) and Stroop test were evaluated. Biochemical analyzes were performed on blood and urine. For statistical analysis the General Linear Model (GLM) of repeated measures was used for comparison between groups. Results: Regarding biochemical and urinary parameters, the LR group presented higher LDL cholesterol fraction (KS: 102.9 ± 24.0 vs CTL: 92.4 ± 33.0 mg / dL, p = 0.02), blood glucose (KS: 87.5 ± 8.5 vs CTL: 80.3 ± 7.3 mg / dL, p = 0.003) and urinary volume (KS: 1966 ± 789 vs CTL: 1600 ± 574 mL, p = 0.006) compared to the CTL group. During orthostatism the KS group showed orthostatic hypertension during recovery different from the CTL group (SBP, KS: 126 ± 15 vs CTL: 122 ± 9 mmHg, p <0.05 and DBP, KS: 81 ± 8 vs CTL: 79 ± 7mmHg, p <0.05). No differences were observed in heart rate variability and baroreflex sensitivity. In the Stroop test there was no statistical difference between the groups during its performance and recovery. However, differences in the analysis of SBP absolute delta (KS: 9 ± 10 vs CTL: 2 ± 8 mmHg, p <0.05) and HR (KS: 13 ± 7 vs CTL: 8 ± 7bpm, p <0.05) were observed. the groups. Regarding CPT, no statistically significant differences were observed between groups. Conclusion: Subtle evidence of possible autonomic alterations in response to orthostatism and emotional stress testing was found, which could be related to the role of ANS in cardiovascular risk of patients with RS. However, further and more comprehensive studies are needed to determine the possible involvement of ANS in the cardiovascular risk of patients with KS.

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