Effect of dexmedetomidine on action potential duration of rat ventricular myocytes and the role of α2 receptors / 中华麻醉学杂志

ABSTRACT

Objective To evaluate the effect of dexmedetomidine on action potential duration (APD)of rat ventricular myocytes and the role of α2receptors. Methods Eighteen ventricular myocytes acutely isolated from Sprague-Dawley rats by enzymatic hydrolysis were divided into 3 groups(n=6 each) using a random number table dexmedetomidine group(D group), yohimbine group(Y group)and dexmedetomidine plus yohimbine group(DY group). Isolated ventricular myocytes were first perfused for 2 min with Tyrode′s solution alone, and APD at 90% repolarization(APD90)was recorded using whole-cell patch-clamp technique. D, Y and DY groups were subsequently perfused for 2 min with Tyrode′s solution containing dexmedetomidine 10-9mol∕L, yohimbine 10-6mol∕L, and dexmedetomidine 10-9mol∕L plus yo-himbine 10-6mol∕L, respectively, and APD90was recorded. The percentage of changes in APD90was calcu-lated. Results Compared with the isolated ventricular myocytes perfused with Tyrode′s solution alone, APD90of ventricular myocytes was significantly prolonged in group D(P<0. 01), and no significant change was found in APD90of ventricular myocytes in Y and DY groups(P>005). The percentage of changes in APD90of ventricular myocytes was significantly shortened in group DY and group Y when com-pared with group D(P<005). Conclusion Dexmedetomidine can prolong APD90of rat ventricular myo-cytes, and the mechanism is related to activating α2receptors.