title: ATP-sensitive and inwardly rectifying potassium channels in smooth muscle.
abstract: The properties and roles of ATP-sensitive (KATP) and inwardly rectifying (KIR) potassium channels are reviewed. Potassium channels regulate the membrane potential of smooth muscle, which controls calcium entry through voltage-dependent calcium channels, and thereby contractility through changes in intracellular calcium. The KATP channel is likely to be composed of members of the inward rectifier channel gene family (Kir6) and sulfonylurea receptor proteins. The KIR channels do not appear to be as widely distributed as KATP channels in smooth muscle and may provide a mechanism by which changes in extracellular K+ can alter smooth muscle membrane potential, and thereby arterial diameter. The KATP channels contribute to the resting membrane conductance of some types of smooth muscle and can open under situations of metabolic compromise. The KATP channels are targets of a wide variety of vasodilators and constrictors, which act, respectively, through adenosine 3',5'-cyclic monophosphate/protein kinase A and protein kinase C. The KATP channels are also activated by a number of synthetic vasodilators (e.g., diazoxide and pinacidil) and are inhibited by the oral hypoglycemic sulfonylurea drugs (e.g., glibenclamide). Together, KATP and KIR channels are important regulators of smooth muscle function and represent important therapeutic targets.
authors.affiliation: Department of Cell Physiology and Pharmacology, University of Leicester, United Kingdom.
authors.forename: J M
authors.initials: JM
authors.lastname: Quayle
authors.forename: M T
authors.initials: MT
authors.lastname: Nelson
authors.forename: N B
authors.initials: NB
authors.lastname: Standen
mesh_terms: D000255:Adenosine Triphosphate / Q000502:physiology*; D000818:Animals; D002545:Brain Ischemia / Q000503:physiopathology; D003920:Diabetes Mellitus / Q000503:physiopathology; D004594:Electrophysiology; D006940:Hyperemia / Q000503:physiopathology; D006973:Hypertension / Q000503:physiopathology; D008564:Membrane Potentials; D009130:Muscle, Smooth / Q000502:physiology*; D009131:Muscle, Smooth, Vascular / Q000502:physiology; D009702:Nucleoside Diphosphate Sugars / Q000494:pharmacology; D018408:Patch-Clamp Techniques; D011188:Potassium / Q000502:physiology; D015221:Potassium Channels / Q000737:chemistry / Q000145:classification / Q000187:drug effects / Q000502:physiology*; D024661:Potassium Channels, Inwardly Rectifying; D011494:Protein Kinases / Q000502:physiology; D012772:Shock, Septic / Q000503:physiopathology; D014662:Vasoconstrictor Agents / Q000494:pharmacology; D014664:Vasodilation / Q000187:drug effects; D014665:Vasodilator Agents / Q000494:pharmacology
chemical_list: D009702:Nucleoside Diphosphate Sugars; D015221:Potassium Channels; D024661:Potassium Channels, Inwardly Rectifying; D014662:Vasoconstrictor Agents; D014665:Vasodilator Agents; D000255:Adenosine Triphosphate; D011494:Protein Kinases; D011188:Potassium