参麦注射液对大鼠膈肌细胞L型钙通道的影响

Effect of Shenmai Injection on L-type Calcium Channel of Diaphragmatic Muscle Cells in Rats

目的 :探讨参麦注射液对大鼠膈肌细胞L型钙通道电流 (ICa L)的影响。方法 :采用急性酶消化分离法 ,获取单个大鼠膈肌细胞 ,用标准的全细胞膜片钳技术 ,记录 7只大鼠膈肌细胞ICa L的峰值及电流 -电压关系曲线 ,并观察不同浓度的参麦注射液对其影响。结果 :当维持电位为 - 80mV ,刺激频率为 0 5Hz,钳制时间为 30 0ms,步进电压为 10mV ,去极到 +6 0mV时 ,10 μl/ml的参麦注射液仅使大鼠膈肌细胞的平均内向峰值ICa L由 (- 6 9± 0 6 )pA/ pF增加到 (- 7 5± 0 7) pA/ pF ,增加的幅度为 (9 2± 2 8) % ,用药前后差异无显著性 (P >0 0 5 )。 5 0 μl/ml、10 0 μl/ml的参麦注射液使大鼠膈肌细胞的平均内向峰值ICa L由 (- 6 9±0 6 ) pA/pF分别增加到 (- 8 4± 0 6 ) pA/ pF和 (- 9 2± 0 6 ) pA/ pF ,其增加的幅度分别为 (2 2 4± 1 7) %和(34 6± 4 6 ) % ,与用药前比较 ,差异均有显著性 (均P <0 0 5 )。给药前后ICa L的最大激活电位和翻转电位均不变。结论 :参麦注射液可激活大鼠膈肌细胞膜的钙通道 ,增加Ca2 + 内流 ,而使膈肌细胞的收缩力增强 ,该作用可能是参麦注射液在临床上用于治疗膈肌疲劳的离子通道机制之一。

Objective:To explore the effect of Shenmai Injection (SMI) on L-type calcium channel of diaphragmatic muscle cells in rats. Methods:Single diaphragmatic muscle cell of rats was obtained by the acute enzyme isolation method and the standard whole-cell patch clamp technique was used to record the inward peak L-type calcium current (IPLC) and current-voltage relationship curve of diaphragmatic muscle cells of 7 rats, and to compare the effects of SMI in various concentrations on them. Results:When keeping the electric potential at -80 mV, stimulation frequency 0.5 Hz, clamp time 300 ms, stepped voltage 10 mV, and depolarized to +60 mV, 10μl/ml of SMI could only cause the mean IPLC of rat′s diaphragmatic muscle cells increased from -6 9±0 6 pA/pF to -7 5±0 7 pA/pF, the amplification being (9 2±2 8)%, comparison between those of pre-treatment and post-treatment showed insignificant difference. But when the concentration of SMI increased to 50μl/ml and 100μl/ml, the mean IPLC increased to -8 4±0 6 pA/pF and -9 2±0 6 pA/pF, respectively, and the amplification was (22 4±1 7)%and (34 6±4 6)% respectively, showing significant difference to that of pre-treatment (P<0 05). However, SMI showed no significant effect on maximal activation potential and reversal potential. Conclusion:SMI can activate the calcium channel of diaphragmatic muscle cells in rats, increase the influx of Ca 2+ , so as to strengthen the contraction of diaphragmatic muscle, which may be one of the ionic channel mechanisms of SMI in treating diaphragmatic muscle fatigue in clinical practice.