Protein Kinase C Modulates Ca^<2+> -Activated K^+ Channels in Cultured Rat Mesenteric Artery Smooth Muscle Cells

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The electrical and pharmacological properties of protein kinase C (PKC) and its effect its effect on the single Ca^<2+> -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 μM) and tetraethylammonium (0.5 μM), but not by apamin (0.4 μM.). In cell-attached patches, bath application of phorbol 12-myristate 13-acetate (PMA, 2 μM), a PKC activator, inhibited the activity of the Kca-channel in the presence of the Ca^<2+> ionophore, A 23187 (10 μM). This inhibition was reversed by subsequent application of staurosporine (1 nM), a PKC inhibitor. Application of 1-oleoyl-2-acetylglycerol (OAG, 30 μM), 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 PMS (1 μM), inhibited the K^+ channel. These results indicate that protein kinase C inhibits the Ca^<2+> -activsted K^+ channel of mesenteric artery smooth muscle cells in the rat.
公益社団法人日本薬学会の論文
2000-12-01