Protein kinase C modulates Ca2+-activated K+ channels in cultured rat mesenteric artery smooth muscle cells.
The electrical and pharmacological properties of protein kinase C (PKC) and its effect on the single Ca2+-activated K+ channel (Kca-channel) in the cultured smooth muscle cells of rat mesenteric artery were studied using a patch-clamp technique. The Kca-channel had a slope conductance of 151+/-7 pS (mean+/-S.E.) in symmetrical 142 mm K solutions. The high conductance K+ channel, applied to the outer side of membrane patches, was potently inhibited by charybdotoxin (0.1 microM) and tetraethylammonium (0.5 microM), but not by apamin (0.4 microM). In cell-attached patches, bath application of phorbol 12-myristate 13-acetate (PMA, 2 microM), a PKC activator, inhibited the activity of the Kca-channel in the presence of the Ca2+ ionophore, A 23187 (10 microM). This inhibition was reversed by subsequent application of staurosporine (1 nM), a PKC inhibitor. Application of 1-oleoyl-2-acetylglycerol (OAG, 30 microM), another PKC activator, also inhibited the A 23187-induced activation of the K+ channel, and this inhibition was reversed by staurosporine. In inside-out patches, bath application of PKC (0.2 munits), in the presence of ATP (1 mM) and PMA (1 microM), inhibited the K+ channel. These results indicate that protein kinase C inhibits the Ca2+-activated K+ channel of mesenteric artery smooth muscle cells in the rat.
Taguchi
K
K
Department of Neuroscience, Showa Pharmaceutical University, Machida, Tokyo, Japan. taguchi@ac.shoyaku.ac.jp
Kaneko
K
K
Kubo
T
T
D000255:Adenosine Triphosphate / Q000494:pharmacology; D000818:Animals; D000001:Calcimycin / Q000494:pharmacology; D002118:Calcium / Q000378:metabolism / Q000494:pharmacology*; D002478:Cells, Cultured; D004553:Electric Conductivity; D004789:Enzyme Activation; D007476:Ionophores / Q000494:pharmacology; D007700:Kinetics; D008297:Male; D008564:Membrane Potentials / Q000187:drug effects / Q000502:physiology; D008638:Mesenteric Arteries / Q000201:enzymology / Q000378:metabolism / Q000502:physiology; D009131:Muscle, Smooth, Vascular / Q000201:enzymology / Q000378:metabolism / Q000502:physiology*; D018408:Patch-Clamp Techniques; D015221:Potassium Channels / Q000187:drug effects / Q000502:physiology*; D011493:Protein Kinase C / Q000037:antagonists & inhibitors / Q000378:metabolism*; D051381:Rats; D017208:Rats, Wistar; D013755:Tetradecanoylphorbol Acetate / Q000494:pharmacology
D007476:Ionophores; D015221:Potassium Channels; D000001:Calcimycin; D000255:Adenosine Triphosphate; D011493:Protein Kinase C; D013755:Tetradecanoylphorbol Acetate; D002118:Calcium