Navegando por Palavras-chave "Cardiac myocytes"

Agora exibindo 1 - 2 de 2
  • Imagem de Miniatura
    Item
    Acesso aberto (Open Access)
    Memantine prevents cardiomyocytes nuclear size reduction in the left ventricle of rats exposed to cold stress
    (Faculdade de Medicina / USP, 2009-01-01) Meneghini, Adriano; Ferreira, Celso [UNIFESP]; Abreu, Luiz Carlos de; Valenti, Vitor Engrácia [UNIFESP]; Ferreira, Marcelo; F. Filho, Celso; Murad, Neif; Faculdade de Medicina do ABC Departamento de Clínica Médica; Universidade Federal de São Paulo (UNIFESP); Universidade de São Paulo (USP)
    OBJECTIVES: Memantine is an N-methyl-d-aspartate (NMDA) glutamate receptor antagonist used to treat Alzheimer's disease. Previous studies have suggested that receptor blockers act as neuroprotective agents; however, no study has specifically investigated the impact that these drugs have on the heart. We sought to evaluate the effects of memantine on nuclear size reduction in cardiac cells exposed to cold stress. METHOD: We used male EPM-Wistar rats (n=40) divided into 4 groups: 1) Matched control (CON); 2) Memantine-treated rats (MEM); 3) Rats undergoing induced hypothermia (IH) and 4) Rats undergoing induced hypothermia that were also treated with memantine (IHM). Animals in the MEM and IHM groups were treated by oral gavage administration of 20 mg/kg/day memantine over an eight-day period. Animals in the IH and IHM groups were submitted to 4 hours of hypothermia in a controlled environment with a temperature of - 8ºC on the last day of the study. RESULTS: The MEM group had the largest cardiomyocyte nuclear size (151 ± 3.5 μm³ vs. CON: 142 ± 2.3 μm³; p<0.05), while the IH group had the smallest mean value of nuclear size. The nuclear size of the IHM group was preserved (125 ± 2.9 μm³) compared to the IH group (108 ± 1.7 μm³; p<0.05). CONCLUSION: Memantine prevented the nuclear size reduction of cardiomyocytes in rats exposed to cold stress.
  • Nenhuma Miniatura disponível
    Item
    Somente Metadadados
    (-)-Terpinen-4-ol changes intracellular Ca2+ handling and induces pacing disturbance in rat hearts
    (Elsevier Science Bv, 2017) Santana Gondim, Antonio Nei; Lara, Aline; Santos-Miranda, Artur; Roman-Campos, Danilo [UNIFESP]; Lauton-Santos, Sandra; Rodrigues Menezes-Filho, Jose Evaldo; Lins de Vasconcelos, Carla Maria; Conde-Garcia, Eduardo Antonio; Guatimosim, Silvia; Cruz, Jader S.
    (-)-Terpinen-4-ol is a naturally occurring plant monoterpene and has been shown to have a plethora of biological activities. The objective of this study was to investigate the effects of (-)-terpinen-4-ol on the rat heart, a key player in the control and maintenance of arterial blood pressure. The effects of (-)-terpinen-4-ol on the rat heart were investigated using isolated left atrium isometric force measurements, in vivo electrocardiogram (ECG) recordings, patch clamp technique, and confocal microscopy. It was observed that (-)-terpinen-4-ol reduced contraction force in an isolated left atrium at millimolar concentrations. Conversely, it induced a positive inotropic effect and extrasystoles at micromolar concentrations, suggesting that (-)-terpinen-4-ol may have arrhythmogenic activity on cardiac tissue. In anaesthetized animals, (-)-terpinen-4-ol also elicited rhythm disturbance, such as supraventricular tachycardia and atrioventricular block. To investigate the cellular mechanism underlying the dual effect of (-)-terpinen-4-ol on heart muscle, experiments were performed on isolated ventricular cardiomyocytes to determine the effect of (-)-terpinen-4-ol on L-type Ca2+ currents, Ca2+ sparks, and Ca2+ transients. The arrhythmogenic activity of (-)-terpinen-4-ol in vitro and in vivo may be explained by its effect on intracellular Ca2+ handling. Taken together, our data suggest that (-)-terpinen-4-ol has cardiac arrhythmogenic activity.