Protein kinase C mediates insulin-inhibited Ca2+ transport and contraction of vascular smooth muscle
| Autor: | A M, Kahn, J C, Allen, C L, Seidel, T, Song |
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| Rok vydání: | 2000 |
| Předmět: |
Male
Manganese Serotonin Biological Transport Free Radical Scavengers Naphthalenes Staurosporine Muscle Smooth Vascular Femoral Artery Dogs Vasoconstriction Carcinogens Animals Hypoglycemic Agents Insulin Tetradecanoylphorbol Acetate Calcium Female Enzyme Inhibitors Fura-2 Cyclic GMP Protein Kinase C Fluorescent Dyes Muscle Contraction |
| Zdroj: | American journal of hypertension. 13(4 Pt 1) |
| ISSN: | 0895-7061 |
| Popis: | Insulin acutely inhibits contraction of primary cultured vascular smooth muscle (VSM) cells from canine femoral artery by inhibiting contractile agonist-induced Ca2+ influx. Insulin also inhibits contraction at step(s) distal to intracellular Ca2+ concentration (Ca2+i) by stimulating cyclic guanosine monophosphate (GMP) production. We wished to see whether these effects of insulin are mediated by protein kinase C (PKC). Ca2+ influx was assessed by measuring the rate of fluorescence quenching of intracellular fura 2 by extracellular Mn2+. We found that 10 micromol/L serotonin (5-HT) stimulated Mn2+ influx 3-fold, and 1 nmol/L insulin inhibited the 5-HT-stimulated component of Mn2+ influx by 63% (P.05), but insulin had no effect in the presence of 1 micromol/L staurosporine, an inhibitor of PKC. In the absence of insulin, preincubating cells with 0.1 micromol/L phorbol 12-myristate 13-acetate (PMA) for 5 min inhibited the 5-HT-stimulated component of Mn2+ influx by 69% (P.05). Insulin inhibited cell contraction induced by raising Ca2+i to supraphysiologic levels with ionomycin by 75% (P.05). We also noted that 10(-6) mol/L calphostin C, another PKC inhibitor, or 16-h preincubation with PMA completely blocked this effect of insulin. Finally, 10-min exposure to insulin or PMA increased cyclic GMP production in ionomycin-treated cells by 50% and 64%, respectively (both P.05). We conclude that insulin inhibits VSM cell contraction by inhibiting 5-HT-stimulated Ca2+ influx and also at step(s) distal to Ca2+i by a PKC-dependent mechanism. |
| Databáze: | OpenAIRE |
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