[Effects of endothelin on electrophysiological and contractile activity of guinea pig papillary muscles].
Effects of endothelin on electrophysiological activity and contractility were examined in guinea pig papillary muscle using intracellular microelectrode and contractile tension recording technique. The results indicated that ET-1 prolonged APD, especially PPD and increased the contractile tension in a dose-dependent manner. The ET-induced effects were not influenced by K+ channel blocker TEA, but inhibited by L-type Ca2+ channel blocker nifedipine, ETA receptor selective antagonist BQ-123 and atriopeptin III in a concentration-dependent manner. It is suggested that the changes in electrophysiological activity and the positive inotropic effect induced by ET-1 in guinea pig muscles are due to the elevation of intracellular calcium, which may be mediated by ETA receptor.
Zhang
Z
Z
Department of Physiology, Hebei Medical University, Shijiazhuang.
Li
Y L
YL
He
R R
RR
D000818:Animals; D001693:Biological Transport, Active; D002118:Calcium / Q000378:metabolism*; D015220:Calcium Channels; D019332:Endothelin-1 / Q000494:pharmacology*; D005260:Female; D006168:Guinea Pigs; D006321:Heart / Q000187:drug effects / Q000502:physiology*; D008297:Male; D008564:Membrane Potentials / Q000187:drug effects; D008839:Microelectrodes; D009200:Myocardial Contraction / Q000187:drug effects*; D010210:Papillary Muscles / Q000187:drug effects / Q000502:physiology*
D015220:Calcium Channels; D019332:Endothelin-1; D002118:Calcium