Navegando por Palavras-chave "vasopressin"

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    Blood flow measurements in rats using four color microspheres during blockade of different vasopressor systems
    (Assoc Bras Divulg Cientifica, 2005-01-01) De Angelis, Katia; Gama, V. M. [UNIFESP]; Farah, VAM; Irigoyen, Maria Claudia [UNIFESP]; Universidade de São Paulo (USP); Universidade Federal de São Paulo (UNIFESP); Univ Santo Amaro; Univ Sao Judas Tadeu
    The use of colored microspheres to adequately evaluate blood flow chancres under different circumstances in the same rat has been validated with a maximum of three different colors due to methodological limitations. the aim of the present study was to validate the use of four different colors measuring four repeated blood flow. changes in the same rat to assess the role of vasopressor systems in. controlling arterial pressure (AP). Red (150,000), white (200,000)), yellow (150,000), and blue (200,000) colored microspheres were infused into the left ventricle of 6 male Wistar rats 1) at rest and 2) after vasopressin (aAVP, 10 mug/kg, iv), 3) renin-angiotensin (losartan, 10 ms/kg iv), and 4) sympathetic system blockade (hexamethonium., 20 mg/kg, iv) to determine blood flow changes. AP was recorded and processed with a data acquisition system (1-kHz sampling frequency). Blood flow changes were quantified by spectrophotometry absorption peaks for colored microsphere components in the tissues evaluated. Administration of aAVP and losartan slightly reduced the AP (-5.7 +/- 0.5 and -7.8 +/- 1.2 mmHg, respectively), while hexamethonium induced a 52 +/- 3 mmHg fall in AP. the aAVP injection increased blood flow in lungs (78%), liver (117%) and skeletal muscle (>150%), while losartan administration enhanced blood flow in heart (126%), lungs (100%), kidneys (80%), and gastrocnemius (75%) and soleus (94%) muscles. Hexamethonium administration reduced only kidney blood flow (50%). in conclusion, four types of colored microspheres can be used to perform four repeated blood flow measurements in the same rat detecting small alterations such as changes in tissues with low blood flow.
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    Cardiovascular mechanisms activated by microinjection of baclofen into NTS of conscious rats
    (Amer Physiological Soc, 2003-03-01) Landulpho, Carlos Daniel Almeida Pitanga; Dias, Ana Carolina Rodrigues; Colombari, Eduardo [UNIFESP]; Universidade Federal de São Paulo (UNIFESP)
    The peripheral mechanisms responsible for pressor response produced by microinjections of baclofen (GABA(B) agonist) into the nucleus tractus solitarii (NTS) of conscious rats were studied. Bilateral microinjections of baclofen (10-1,000 pmol/100 nl) produced a dose-related increase in mean arterial pressure (MAP) and heart rate. the maximal response was observed after 15 min. Intravenous injection of prazosin decreased MAP to control levels. Subsequent treatment with Manning compound (vasopressin receptor antagonist; iv) produced an additional decrease in MAP. in a different group of rats, vasopressin antagonist was injected first and MAP was significantly decreased; however, it remained elevated compared with prebaclofen injection levels. Subsequent treatment with prazosin abolished the baclofen-induced pressor response. Reductions in baclofen-induced pressor response with prazosin treatment were followed by a reflex tachycardia in animals that received a 100 pmol/100 nl dose of baclofen. the tachycardia was not observed with a dose of 1,000 pmol/100 nl. the pressor response induced by microinjection of baclofen into the NTS of conscious rats may be produced by both increases in sympathetic tonus and vasopressin release.
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    Enhanced pressor response to carotid occlusion in commNTS-lesioned rats: possible efferent mechanisms
    (Amer Physiological Soc, 2000-05-01) Sato, Monica Akemi [UNIFESP]; Menani, Jose Vanderlei; Lopes, Oswaldo Ubriaco [UNIFESP]; Colombari, Eduardo [UNIFESP]; Universidade Federal de São Paulo (UNIFESP); Univ Estadual Paulista
    Bilateral common carotid occlusion (BCO) over a period of 60 s in conscious rats produces a biphasic presser response, consisting of an early (peak) and late (plateau) phase. In this study we investigated 1) the effects of lesions of the commissural nucleus of the solitary tract (commNTS) on the cardiovascular responses produced by BCO in conscious rats and 2) the autonomic and humoral mechanisms activated to produce the presser response to BCO in sham- and commNTS-lesioned rats. Both the peak and plateau of the presser response produced by BCO increased in commNTS-lesioned rats despite the impairment of chemoreflex responses induced by intravenous potassium cyanide. In sham rats sympathetic blockade with intravenous prazosin and metoprolol, but not vasopressin receptor blockade with the Manning compound, reduced both components of BCO. In commNTS-lesioned rats the sympathetic blockade or vasopressin receptor blockade reduced both components of BCO. The results showed 1) the sympathetic nervous system, but not vasopressin, is important for the presser response to BCO during 60 s in conscious sham rats; 2) in commNTS-lesioned rats, despite chemoreflex impairment, BCO produces an increased presser response dependent on sympathetic activity associated with vasopressin release; and 3) the increment in the presser response to BCO in commNTS-lesioned rats seems to depend only on vasopressin secretion.
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    Plasma copeptin and metabolic dysfunction in individuals with bipolar disorder
    (Wiley, 2017) Mansur, Rodrigo B. [UNIFESP]; Rizzo, Lucas B. [UNIFESP]; Santos, Camila M. [UNIFESP]; Asevedo, Elson [UNIFESP]; Cunha, Graccielle R. [UNIFESP]; Noto, Mariane N. [UNIFESP]; Pedrini, Mariana [UNIFESP]; Zeni-Graiff, Maiara [UNIFESP]; Cordeiro, Quirino; McIntyre, Roger S.; Brietzke, Elisa [UNIFESP]
    AimThis study aimed to compare plasma copeptin levels, the c-terminal of provasopressin, between individuals with bipolar disorder (BD) and healthy controls and to assess the relation between copeptin and metabolic parameters. MethodsWe measured plasma levels of copeptin in individuals with BD (n=55) and healthy controls (n=21). Information related to psychiatric/medical history, as well as to metabolic comorbidities and laboratorial parameters was also captured. Insulin resistance and -cell function in basal state were calculated from fasting plasma glucose and C-peptide using the HOMA2 calculator. Impaired glucose metabolism was defined as pre-diabetes or type 2 diabetes mellitus. Copeptin, adiponectin, and leptin plasma levels were determined by enzyme-linked immunosorbent assay. ResultsPlasma copeptin levels were lower in individuals with BD, relative to healthy controls (P<0.001). There were significant interactions between BD and plasma copeptin on -cell function (rate ratio [RR]=1.048
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    Role of vasopressin in 24-hour blood pressure regulation in diabetic patients with autonomic neuropathy
    (Elsevier B.V., 2002-01-01) Monteagudo, P. T.; Gavras, H.; Gavras, I; Kohlmann, O.; Ribeiro, A. B.; Zanella, M. T.; Universidade Federal de São Paulo (UNIFESP); Boston Univ
    To evaluate the role of vasopressin (AVP) on blood pressure (BP) in diabetic patients with autonomic neuropathy (AN), 10 patients were studied on a fixed sodium and potassium diet. On days 4 and 7, a 24-h BP monitoring, as well as blood and urine samples for sodium, potassium, creatinine, and osmolality determinations were obtained for every 4-h period either placebo or an AVP-V-1-antagonist (d(CH2)(5)Tyr(me)AVP; 0.5 mg; AVP(i)) were given iv at 1 PM. On placebo, systolic BP (SBP) showed a progressive elevation during the day, declining after 12 Pm (8 AM to 12 AM 122 +/- 9; 12 AM to 4 PM 125 +/- 11; 4 PM to 8 PM 134 +/- 14; 8 PM to 12 PM 136 +/- 14, 12 PM to 8 AM 131 +/- 17 mm Hg). On AVP(i) this rise in SBP was blunted: 8 AM to 12 AM 125 +/- 122; 12 AM to 4 PM 121 +/- 21; 4 PM to 8 PM 126 +/- 16; 8 PM to 12 PM 129 +/- 14; 12 PM to 8 AM 124 12 mm Hg. Creatinine clearance and diureses were greater during the night, both with placebo and AVP(i). Plasma osmolality did not change on either day, although serum sodium decreased after AVP(i), reaching the lowest values at 4 PM to 8 PM period (137 +/- 4.7 v 131 +/- 3.8 mEq/L; P < .05). With placebo, fractional excretion of sodium (FENa increased from 0.43% +/- 0.32% during 12 h of orthostasis to 0,92% +/- 1.05% during 12 h of recumbency (P < .02). With AVP(i), the FENa on orthostasis did not differ from that with placebo, although BP values were lower and did not increase with recumbency (0.58 +/- 0.57 v 0.73% +/- 0.49%; NS). in conclusion, our results show that in diabetic patients with AN, vasopressin participates in BP control by stimulating vascular and renal V-1 receptors, which results in vasoconstriction and sodium reabsorption. (C) 2002 American Journal of Hypertension, Ltd.
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    Suppression of adrenocorticotrophic hormone secretion by simultaneous antagonism of vasopressin 1b and CRH-1 receptors on three different stress models
    (Karger, 2006-01-01) Ramos, Adriana T.; Troncone, Lanfranco R. P.; Tufik, Sergio [UNIFESP]; Inst Butantan; Universidade Federal de São Paulo (UNIFESP)
    Background/Aims: Corticotrophin-releasing hormone (CRH), adrenocorticotrophic hormone (ACTH) and corticosterone are secreted during stress. These mediators may be involved in anxiety, depression and post-traumatic stress disorder, therefore antagonists have been developed to treat such conditions. Methods: the non-peptide CRH receptor type 1 antagonist CP154,526 and the vasopressin receptor type 1b antagonist SSR149415 were used to suppress the secretion of ACTH induced by ether exposure, forced swimming and restraint in adult male Wistar rats. Doses ranged from 3 to 60 mg/kg s.c. (controls with vehicle) alone or in combination, in varying time schedules to assess the duration and effectiveness of treatments. Results: Stressors increased plasma ACTH by 2.5- to 5-fold in control rats. SSR149415 at doses of 30 mg/kg was more effective at suppressing ACTH secretion after ether exposure and restraint but was ineffective against forced swimming. CP154,526 mildly affected ACTH rise after restraint at doses of 30 mg/kg. the combination of both antagonists at doses of 30 mg/kg effectively blocked the rise in plasma ACTH in all three stresses. the drug effects lasted less than 6 h. Conclusion: We demonstrated for the first time that simultaneous blockade of both vasopressin 1b and CRH-R1 receptors effectively abolish the ACTH response to physical and psychological stress modalities. Copyright (c) 2006 S. Karger AG, Basel