Inability of endothelin to increase Ca2+ current in guinea-pig heart cells. |
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| Authors: | N. Tohse Y. Hattori H. Nakaya M. Endou M. Kanno |
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| Affiliation: | Department of Pharmacology, Hokkaido University School of Medicine, Sapporo, Japan. |
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| 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. |
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