Effects of remifentanil on large-conductance Ca2 ＋ -activated potassium channels in human mesenteric arterial smooth muscle cells

Abstract

Objective To investigate the effects of remifentanil on large-conductance Ca2＋ -activated potassium channel （BKCa） in human mesenteric arterial smooth muscle cells （MASMCs） and the mechanism of the vasorelaxant effect of remifentanil. Methods Human MASMCs were obtained freshly by the method of enzymolysis. BKCa current （IBKCa） was recorded by the whole-cell patch clamp technique. The changes in IBKC. produced by different concentrations of remifentanil （1.2, 4.8, 19.4, 77.4 and 310.0 nmol/L） with the holding potential of ＋ 80 mV were observed. BKCa activation rate was calculated. Results Remifentanil significantly increased IBKCa,moved Ⅰ-Ⅴ curve upward and had no effect on the threshold of activation for IBKCa . With the increase in the concentration of remifentanil, BKCa activation rate increased gradually （P 〈 0.01）, and it remained stable when the concentration reached 19.4 nmol/L. There was no significant difference in the peak time of IBKCa after different concentrations of remifentanil were given （P 〉 0.05）. Logarithmic curve was found to suit the relationship between the concentration of remifentanil and BKCa activation rate and the IC50 concentration was （118 ± 7） nmol/L. Conclusion Remifentanil results in vasorelaxation by activating BKCa in MASMCs in a concentration-dependent manner. Key words: Piperidines; Calcium-activated potassium channels; Mesenteric arteries; Myocytes,smooth muscle