ATP-dependent potassium channels of muscle cells: Their properties,regulation, and possible functions |
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Authors: | N W Davies N B Standen P R Stanfield |
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Institution: | (1) Department of Physiology, University of Leicester, P.O. Box 138, LE1 9HN Leicester, UK |
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Abstract: | ATP-dependent potassium channels are present at high density in the membranes of heart, skeletal, and smooth muscle and have a lowP
open at physiological ATP]i. The unitary conductance is 15–20 pS at physiological K+]
o
, and the channels are highly selective for K+. Certain sulfonylureas are specific blockers, and some K channel openers may also act through these channels. KATP channels are probably regulated through the binding of ATP, which may in turn be regulated through changes in the ADP/ATP ratio or in pHi. There is some evidence for control through G-proteins. The channels have complex kinetics, with multiple open and closed states. The main effect of ATP is to increase occupancy of long-lived closed states. The channels may have a role in the control of excitability and probably act as a route for K+ loss from muscle during activity. In arterial smooth muscle they may act as targets for vasodilators. |
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Keywords: | potassium channel potassium current ATP skeletal muscle smooth muscle vasodilator metabolic exhaustion |
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