缺血再灌注处理对乳鼠心肌细胞钠电流的影响

Effects of ischemia/reperfusion management on the sodium current of the cardiocytes from the new-born rats

目的研究缺血再灌注(I/R)处理对乳鼠心肌细胞钠电流的影响。方法实验分为两组:对照组为体外培养乳鼠心室肌细胞;I/R组为相同的细胞,缺血3 h,再灌注1 h,采用膜片钳全细胞模式记录仪分别记录并比较对照组和I/R组的钠电流。结果和对照组相比,I/R组在每一指令电压上都增大钠电流;在测试电压为-20 mV的条件下,钠电流峰值电流密度从(-159.74±63.80)pA/pF增至(-397.25±82.99)pA/pF(n=7,P(0.05);通道稳态激活V1/2分别为(-58.77±3.83)mV和(-51.51±5.34)mV(n=5,P(0.05);稳态失活V1/2分别为(-58.77±3.83)mV和(-51.51±5.34)mV(n=5,P(0.05);通道失活后恢复τ分别为(8.57±1.50)ms和(6.30±0.57)ms(n=5,P(0.05)。结论 I/R处理可以增大钠电流的峰值电流,并使电压电流曲线下移;减慢通道的时间依赖性激活,促进通道的电压依赖性失活,失活后恢复变快。钠通道的这些改变可能是引起心肌细胞缺血再灌注损伤的重要原因。

OBJECTIVE To study the effects of ischemia/reperfusion（I/R）management on the sodium current of the cardiocyte from the ventricle of the new-born rat.METHODS The cells were classified into two groups： the normal cardiocyte from new-born rat（control group） and the same cardiocyte that were treated under the condition of three hours ischemia and one hour reperfusion（I/R group）.The sodium currents from the control group and I/R group were recorded and compared by whole cell patch clamp technique.RESULTS Compared with the control group,the sodium currents of all the cardiocyte from the I/R group at all the test potentials increased.At the test potential of-20 mV,the peak sodium current increased from（-159.74±63.80）（pA/pF） to（-397.25±82.99）（pA/pF）（n=7,P〈0.05）;V1/2 of the steady-state activation were（-58.77±3.83） mV and（-51.51±5.34） mV（n=5,P〈0.05）;V1/2 of the steady-state inactivation were（-58.77±3.83） mV and（-51.51±5.34） mV（n=5,P〈0.05）;channel recovery time constant were（8.57±1.50） ms and（6.30±0.57） ms（n=5,P〈0.05）.CONCLUSION I/R management could increase the peak sodium current,down-shift the voltage-current curve,slow the time-dependent activation of the sodium channel and promote inactivation of voltage-dependent of the sodium channel.Changes of the sodium channel could play an important role in the I/R injury of cardiocyte.