高胰岛素水平对血管平滑肌细胞NO生成的影响

培养大鼠血管平滑肌细胞 (VSMC) ,检测高胰岛素 (HI)对VSMC膜蛋白激酶C(PKC)活性的影响 ;并采用硝酸还原酶法和免疫印迹法检测HI加或不加PKC抑制剂 -H7对脂多糖 (LPS) +γ -干扰素 (γ -IFN)诱导NO生成和一氧化氮合酶 (iNOS)表达的影响。结果 ,HI预处理的VSMC ,膜PKC活性明显高于对照 (P <0 .0 5 ) ;LPS +γ -IFN诱导NO生成显著低于对照 (P <0 .0 1) ,加H7培育 ,NO的生成量较HI处理组明显提高 ,但低于对照 (P <0 .0 1)。免疫印迹示HI处理的VSMC ,iNOS表达下降。提示 :高胰岛素血症可能通过激活VSMC膜PKC ,部分抑制iNOS表达 ,减少NO产生。

Effect of hyperinsulinism on NO production in vascular smooth muscle cells

Nitrate reductasing and immunoblotting test were used to investigate the modulation of protein kinase C (PKC) activity in cultured rat vascular smooth muscle cells (VSMCs) with high concentration of insulin(HI) and the effect of HI on lipopolysaccharides+γ-interferon (LPS+γ-IFN)-induced nitric oxide (NO) production and inducible nitric oxide synthase (iNOS) expression with or without PKC inhibitor H 7 . The results were that membrane PKC activity preincubated with HI was significantly higher than that with the control group(P<0.05), and NO production pretreated by HI was obviously lower than that of the control group(P<0.01). PKC inhibitor H 7 ameliorated the down-regulation of LPS+γ-IFN induced NO production by high concentration of insulin. Immunoblotting test revealed a decrease induced by the high level insulin in the expression of iNOS in VSMCs. It is suggested that hyperinsulinism may activate PKC to partly inhibit the expression of iNOS and decrease NO production in VSMCs.