title: An ATP, calcium and voltage sensitive potassium channel in porcine coronary artery smooth muscle cells.
abstract: There is increasing interest in the roles played by potassium channels of smooth muscle in protecting against ischemic and anoxic insults. Hence, potassium-selective channels were studied in freshly dispersed porcine coronary artery smooth muscle cells using the inside-out variant of the patch-clamp technique. The most abundant potassium channel had a conductance of 148 pS in a 5.4/140 mM K+ gradient, at 0 mV, and was regulated by cytoplasmic ATP (0.05-3.0 mM), cytoplasmic Ca2+ (0.1-10 microM) and voltage. ATP and AMP-PNP (0.5 mM) reduced the probability of channel opening (Po) by 87 and 92%, respectively. This inhibition was partially reversed by the addition of 0.5 mM ADP. ADP on its own (2 mM) reduced Po by 46%. It appears, therefore, that this channel shares properties with both the ATP-sensitive and the calcium-regulated potassium channels, raising the possibility that it plays a central role in the regulation of coronary blood flow.
authors.affiliation: Department of Molecular and Cellular Pharmacology, University of Miami School of Medicine, FL 33101.
authors.forename: S D
authors.initials: SD
authors.lastname: Silberberg
authors.forename: C
authors.initials: C
authors.lastname: van Breemen
mesh_terms: D000244:Adenosine Diphosphate / Q000494:pharmacology; D000255:Adenosine Triphosphate / Q000378:metabolism* / Q000494:pharmacology; D000266:Adenylyl Imidodiphosphate / Q000494:pharmacology; D000818:Animals; D002118:Calcium / Q000494:pharmacology / Q000502:physiology*; D003331:Coronary Vessels / Q000502:physiology*; D004553:Electric Conductivity; D066298:In Vitro Techniques; D007700:Kinetics; D009131:Muscle, Smooth, Vascular / Q000502:physiology*; D015221:Potassium Channels / Q000187:drug effects / Q000502:physiology*; D013552:Swine
chemical_list: D015221:Potassium Channels; D000266:Adenylyl Imidodiphosphate; D000244:Adenosine Diphosphate; D000255:Adenosine Triphosphate; D002118:Calcium