伊布利特对兔急性心肌梗死后梗死周边区心外膜心室肌细胞L型钙电流的影响

目的观察伊布利特对急性心肌梗死(AMI)后一周心室肌细胞L型钙通道电流(ICa-L)的影响。方法兔开胸,左前降支结扎造成AMI,1周后酶解分离梗死周边区心外膜心室肌细胞,用全细胞膜片钳技术记录10-6mol/L伊布利特细胞外液(伊布利特组)对梗死周边区心外膜心室肌细胞ICa-L活性的影响,并与正常对照组(对照组)及AMI但未灌流伊布利特组(AMI组)比较。结果①AMI 1周时兔梗死周边区心室肌细胞ICa-L受到抑制,电流密度-电压曲线(I-V)上移,ICa-L电流密度峰值降低[-3.52±0.91 pA/pF(n=10)vs-5.68±1.53 pA/pF(n=10),P<0.05];伊布利特组电流密度峰值为-4.84±1.22 pA/pF(n=8),较AMI组显著增大(P<0.05),与对照组比较,虽有减小,但无差异(P>0.05)。②AMI组、伊布利特组ICa-L失活曲线明显左移,以AMI组左移更加明显,对照组半数失活电压(V0.5)为-32±4 mV(n=10),AMI组V0.5增加为-46±7 mV(n=10,P<0.05),伊布利特组V0.5为-36±6mV(n=8),与对照组比较无差异(P>0.05)。结论AMI后1周梗死周边带心室肌细胞L型钙通道受阻滞,伊布利特对缺血引起的ICa-L的异常有明显改善作用。

Effects of ibutilide on L-type Ca2+ current in ventricular myocytes from infracted rabbit hearts

Objective To study the effects of ibutilide on L-type Ca^2＋ current（ ICa-L） of myocardial cells from the epieardial border zone of the 1-week infracted rabbit hearts. Methods Acute myocardial infraction （AMI） was induced by ligating of the left anterior descending coronary artery. 1 week later, ICa-L was recorded using whole cell patch-clamp techniques and the effects of ibutilide on LCa-L current of cells from the epicardial border zone of the 1-week infracted rabbit hearts were observed . Results Peak ICa-L density （ at 0 mV） was significantly reduced in AMI group （ - 3.52 ± 0.91 pA/pF, n = 10） than that in control group （ - 5.68 ±1.53 pA/pF, n = 10） ,P 〈 0.05. However, the peak ICa-L, density in ibutilide group （ -4.84 ±1.22 pA/pF, n = 8 ） was not significantly different from that of the control group. There were also significantly different between AMI and ibutilide group （P 〈 0.05 ）. The haft inactivation potential （V0.5 ） was -32 ± 4 mV （ n = 10） in control group, and - 46 ± 7 mV （ n = 10 ） in AMI group and - 36 ± 6 mV （ n = 8 ） in ibutilide group respectively, which showed significantly different between control group and AM1 group （ P 〈 0. 05 ）. Conclusion ICa-L is reduced, and its kinetics alters in myocytes of the infracted zone. The depressed lea_L returns to nearly normal by ibutilide.