Endothelin increases single-channel calcium currents in coronary arterial smooth muscle cells.
Endothelin (ET), a newly identified vasoconstrictor peptide produced by endothelial cells, depends on extracellular calcium for its action [(1988) Nature 332, 411-415]. It is not yet known whether the increase in calcium influx induced by ET results from a direct effect on the Ca2+ channels or is secondary to a reduction in membrane potential. To address this question, we studied the effects of ET on single-channel calcium currents of freshly dissociated porcine coronary artery smooth muscle cells using the cell-attached mode of the patch-clamp technique. We show that ET increases Ca2+-channel activity with no effect on channel open time or conductance. The ability of bath-applied ET to increase single-channel calcium currents in the cell-attached mode is evidence that the peptide acts via a second messenger system.
Silberberg
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Department of Physiology and Molecular Biophysics, Baylor College of Medicine, Houston, TX 77030.
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Lacerda
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D001498:3-Pyridinecarboxylic acid, 1,4-dihydro-2,6-dimethyl-5-nitro-4-(2-(trifluoromethyl)phenyl)-, Methyl ester / Q000494:pharmacology; D000818:Animals; D015220:Calcium Channels / Q000187:drug effects / Q000502:physiology*; D003331:Coronary Vessels; D004095:Dihydropyridines / Q000494:pharmacology; D004553:Electric Conductivity; D016232:Endothelins; D004730:Endothelium, Vascular; D008564:Membrane Potentials; D009119:Muscle Contraction / Q000187:drug effects; D009131:Muscle, Smooth, Vascular / Q000187:drug effects / Q000502:physiology*; D010455:Peptides / Q000494:pharmacology*; D015290:Second Messenger Systems; D013552:Swine
D015220:Calcium Channels; D004095:Dihydropyridines; D016232:Endothelins; D010455:Peptides; D001498:3-Pyridinecarboxylic acid, 1,4-dihydro-2,6-dimethyl-5-nitro-4-(2-(trifluoromethyl)phenyl)-, Methyl ester; C038806:1,4-dihydropyridine