慢性低氧对大鼠膈肌细胞L型钙通道电流的影响

Effects of Chronic Hypoxia on L-type Calcium Channel Current of Diaphragmatic Muscle Cells in Rats

目的 研究慢性低氧对急性分离的大鼠膈肌细胞L型钙通道电流的影响。方法 采用标准的全细胞膜片钳 (wholecellpatchclamp)技术 ,记录并比较正常对照组与慢性低氧组大鼠单个膈肌细胞的膜电容 ,L型钙电流的峰值和电流 电压关系曲线。结果 正常对照组与慢性低氧组大鼠单个膈肌细胞的膜电容分别为 (15 0 0± 12 6 )pF和(174 0± 13 3)pF ,低氧组显著大于正常对照组 (P <0 0 5 ,n =6 ) ;L型钙电流的峰值分别为 (- 1 0 5± 0 19)nA和(- 0 97± 0 16 )nA ,两组之间无显著差异。当膜电位处于 - 2 0～ +40mV时 ,慢性低氧组大鼠单个膈肌细胞的L型钙电流密度 [(- 5 6± 0 8)pA/pF]较正常对照组 [(- 7 0± 1 4 )pA/pF]显著下降 (P <0 0 5 ,n =6 )。结论 慢性低氧能使大鼠单个膈肌细胞的膜电容增加 ,L型钙电流的幅度不变 ,因此L型钙电流密度下降。

Objective To study the effects of chronic hypoxia on L-type calcium channel current of single diaphragmatic muscle cells in rats. Methods Whole cell patch clamp technique was employed to record the membrane capacity (Cm) and inner peak of diaphragmatic muscle cells. Results The Cm and inner peak L-type Ca 2+ current of normal control group and chronic hypoxia group were(150.0±12.6) pF vs (174.0±13.3) pF, and (-1.05±0.19)nA vs(-0.97±0.16)nA, respectively. There was a significant reduction in L-type Ca 2+ current density of chronic hypoxia group as compared with normal control group from -20 mV to +40 mV. Conclusion Chronic hypoxia can result in an increase of Cm and cause the reduction of L-type Ca 2+ current density without significant change of the amplitude of L-type Ca 2+ current.