title: Inability of endothelin to increase Ca2+ current in guinea-pig heart cells.
abstract: 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.
authors.affiliation: Department of Pharmacology, Hokkaido University School of Medicine, Sapporo, Japan.
authors.forename: N
authors.initials: N
authors.lastname: Tohse
authors.forename: Y
authors.initials: Y
authors.lastname: Hattori
authors.forename: H
authors.initials: H
authors.lastname: Nakaya
authors.forename: M
authors.initials: M
authors.lastname: Endou
authors.forename: M
authors.initials: M
authors.lastname: Kanno
mesh_terms: 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
chemical_list: D015220:Calcium Channels; D016232:Endothelins; D010455:Peptides; D012433:Ryanodine