Activation of ATP-sensitive K+ channels by cyclic AMP-dependent protein kinase in cultured smooth muscle cells of porcine coronary artery.
The effects of cyclic AMP-dependent protein kinase on ATP-sensitive K+ channels in cultured smooth muscle cells of the porcine coronary artery were investigated using the patch-clamp technique. Extracellular application of isoproterenol (1mM), a beta agonist, or forskolin (2 x 10(-5)M), an activator of adenylate cyclase, activated these channels in cell-attached patch configurations, which were not blocked by phorbol 12-myristate 13-acetate (10(-6)M), an activator of protein kinase C. Cyclic AMP-dependent protein kinase activated these channels in inside-out patch configurations. These results suggest that cyclic AMP-dependent phosphorylation modulates ATP-sensitive K+ channels, in addition to its well known effects on Ca(2+)-activated K+ channels. The activation of ATP-sensitive K+ channels by cyclic AMP-dependent phosphorylation contributes to hyperpolarization of the membrane and to the relaxation of vascular smooth muscle cells.
Second Department of Internal Medicine, School of Medicine, University of Tokushima, Japan.
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H
Miyoshi
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Nakaya
D000255:Adenosine Triphosphate / Q000378:metabolism*; D000818:Animals; D002478:Cells, Cultured; D003331:Coronary Vessels / Q000166:cytology; D008564:Membrane Potentials; D009131:Muscle, Smooth, Vascular / Q000166:cytology / Q000378:metabolism* / Q000502:physiology; D010766:Phosphorylation; D015221:Potassium Channels / Q000187:drug effects / Q000378:metabolism*; D011494:Protein Kinases / Q000502:physiology*; D013552:Swine
D015221:Potassium Channels; D000255:Adenosine Triphosphate; D011494:Protein Kinases