异丙酚对家兔心室外膜心肌细胞动作电位和L-型钙电流的影响

Effects of propofol on action potential and L-type calcium channel curent of subepicardial myocytes of ventricular walls of rabbits.

目的研究异丙酚对家兔左、右心室心外膜心肌细胞动作电位和L-型钙电流的影响。方法酶解法分离家兔左、右心室心外膜心肌细胞。全细胞膜片钳技术记录左、右心室心外膜心肌细胞动作电位和L-型钙电流(ICa-L)在使用异丙酚前后的变化。结果在电流钳制下,左、右心室心外膜心肌细胞动作电位都具有从0期到4期的动作电位形态,2相平台期有心外膜心肌细胞特有的穹窿样突起。异丙酚使右室心外膜心肌细胞动作电位失去2相平台期穹窿样突起,呈三角形尖锥锋形。左、右心室心外膜心肌细胞动作电位时程复极化50%和90%(APD50和APD90)在异丙酚作用后都明显缩短,其中右室心外膜心肌细胞APD50和APD90缩短最为明显(P<0.05或0.01)。在电压钳制下,异丙酚使左、右心室心外膜心肌细胞ICa-L在同一指令电位下,电流幅度均明显减小,但右室心外膜心肌细胞ICa-L的减小幅度明显强于左室同层ICa-L的减小幅度(P<0.01)。异丙酚还使左、右心室心外膜心肌细胞ICa-L的I-V曲线上移,并且使右室心外膜心肌细胞ICa-L的I-V曲线处在所有I-V曲线最上部。结论异丙酚对右室心外膜心肌细胞动作电位和ICa-L的影响程度明显强于左室,从而引起左、右心外膜心肌细胞电不均一性。

Objective To investigate effects of propofol on action potential （AP） and L-type calcium channel curent （ICa-L） of subepicardial myocytes of both left and right ventricular walls of rabbits. Methods The subepicardial myo- cytes were obtained by enzymatic dissociation in left and right ventrieular walls of rabbits. AP and ICa-L were recorded via whole-cell patch-clamp technique. Results According to eurrent clamp protocol, APs which were recorded in subepiear- dial myoeytes of both left and right ventricular walls consisted of five phases from upstroke to phase four, and were attached to a dome in the second plateau of the APs before propofol adminstration. Nonetheless, Propofol（250μmol/L） deleted the dome of the second plateau of the APs of subepieardial myoeytes of left and right ventricular wails, which had not the sec- ond plateau and was shaped an acute triangle in APs of fight subepicardial myoeytes. Propofol significantly shortend the APD5o and APD9o in right and left subepieardium, and right subepieardium were more obvious during the voltage clamp protocol. Propofol （250μmol/L） significantly attenuated the peak amplitude of ICa-L and right subepieardium were more obvi- ous those of that in left subepicardium（P 〈0. O1 ）. Propofol shifted upward the I-V curve of Ica.L of both left and right sub- epieardial myoeytes, hut lifted outstandingly the I-V curve of ICa-L of right subepicardial myocytes on the top of all I-V curves. Conclusion Propofol attenuated more significantly on the APs and ICa-L of subepicardial myoeytes of right ventrieular wall than those of the same layer of left ventricular wall, so that induces cardiac electrical heterogeneity of subepi- cardial myocytes of both left and right ventricular walls. [ Chinese Journal of Cardiac Pacing and Electrophysiology ,2008 ,22 （5） ：438 -441 ]