Effects of Streptozotocin-Induced Diabetes on Kv Channels in Rat Small Coronary Smooth Muscle Cells

Qiang Chai ； Zhixiang Liu ； Lianbi Chen

《The Chinese Journal of Physiology》 48卷1期 (2005/03) Pp. 57-63

並列摘要

Diabetes impairs endothelium dependent vasodilation, but the mechanism of endothelium independent dilation is not well understood. In the present study, we examined the effect of streptozotocin (STZ)-induced diabetes on the vasomotor of small coronary artery and the activity of voltage-dependent K channel of vascular smooth muscle cells in STZ rat using the videomicroscopy and patch clamp method. STZ-induced diabetes appeared reduce the vasodilation induced by β-adrenoceptor agonist, isoproterenol (10(superscript -9)-10(superscript -5) mol/l), and adenylyl cyclase activator forskolin (10(superscript -9)-10(superscript -5) mol/l) respectively (isoproterenol: 44.2±6.7% vs. 82.5±4.8%, and forskolin: 54.4±4.5% vs. 94.3±2.4%). 4-AP, a Kv channel blocker of VSMC, further decreased dilation to isoproterenol (44.2±6.7% vs. 10.2±3.5%) and forskolin (54.4±4.5% vs. 13.8±11.0%) significantly. Whole cell K^+ current recording demonstrated that STZ-induced diabetes decreased isoproterenol and forskolin-induced K^+ current (ISO: 55.6±7.8 pA/pF vs. 28.4±3.4 pA/pF, forskolin: 61.3±9.8 pA/pF vs. 32.4±3.4 pA/pF). 4-AP further reduced the decreased K^+ current (ISO: 28.4±3.4 pA/pF vs. 14.3±2.1 pA/pF, forskolin: 32.4±3.4 pA/pF vs. 14.8±2.9 pA/pF). These results indicated that STZ-induced diabetes impaired cAMP mediated dilation of small coronary artery and suppressed the Kv channel activity of vascular smooth muscle cells. Kv channel of VSMC was shown to play a determinate role reducing dilation of small coronary artery in STZ rats.

並列關鍵字

streptozotocin induced diabetes of rat ； small coronary artery ； voltage K^+ channel ； isoproterenol ； forskolin

參考文獻

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