Inability of endothelin to increase Ca2+ current in guinea-pig heart cells.
Effects of endothelin, a novel vasoconstrictor peptide derived from vascular endothelial cells, on cardiac contractility and membrane currents, were examined in guinea-pig cardiac preparations. Endothelin (3-1000 nM) produced a positive inotropic effect in papillary muscles in a concentration-dependent manner. In whole-cell voltage clamp recording, endothelin (250 nM) decreased the amplitude of Ca2+ current (ICa, 25.0 +/- 6.6%) in ventricular myocytes. The endothelin-induced decrease in ICa was abolished by pretreatment with ryanodine (1 microM). These results suggest that endothelin does not activate cardiac sarcolemmal Ca2+ channels. The enhancement of the sarcoplasmic reticulum function may play an important role in the positive inotropic effect of endothelin.
Tohse
N
N
Department of Pharmacology, Hokkaido University School of Medicine, Sapporo, Japan.
Hattori
Y
Y
Nakaya
H
H
Endou
M
M
Kanno
M
M
D000818:Animals; D015220:Calcium Channels / Q000187:drug effects*; D004558:Electric Stimulation; D016232:Endothelins; D006168:Guinea Pigs; D066298:In Vitro Techniques; D009200:Myocardial Contraction / Q000187:drug effects; D009206:Myocardium / Q000166:cytology / Q000378:metabolism*; D010210:Papillary Muscles / Q000166:cytology / Q000378:metabolism; D010455:Peptides / Q000494:pharmacology*; D012433:Ryanodine / Q000494:pharmacology
D015220:Calcium Channels; D016232:Endothelins; D010455:Peptides; D012433:Ryanodine