内皮素-1对肾小球系膜细胞内游离钙浓度影响

Effect of Endothelin-1 on Cytosolic Free Calcium in Cultured Glomerular Mesangial Cells

ET－1激发肾小球系膜细胞（glomerularmesangialcell，GMC）内［Ca2+］i；升高作用分2个时相，即瞬时峰值升高和缓慢持久升高，对峰值升高呈剂量依赖方式，＜10－10mol／L不引起峰值升高，≥10－10mol／L引起峰值升高，且随着剂量增加，幅度增大。维拉帕米对ET－1激发GMC内［Ca2+］i峰值升高和持久升高均无抑制作用；细胞内储存钙释放抑制剂TMB－8明显抑制峰值升高，但对持久升高无作用；无钙缓含冲液（1mol／LEGTA处理）对峰值升高无作用，但可完全阻止持久升高作用。结果表明ET－1激发GMC内［Ca2+］i浓度峰值升高是由细胞内储存钙释放介导的，而持久升高是由细胞外钙流入增加引起的。

The effect of endothelin - 1 on cytosolic free calcium ([Ca2+ ],) was expressed in two phases, the first was a transient peak increase in [Ca2+ ] i and the second a sustained increase in [Ca2+]i. The transient peak [Ca2+]i was dose- dependent, doses of ET- 1<10-10mol/L did not evoke transient peak increase, while≥10-10mol/L evoked transient peak increase and the greater the ET - 1 dosage, the higher the transient peak increase in [Ca2+]i. Verapamil (10-5mol/L) had no effect on the transient peak and the sustained increase in [Ca2+]i evoked by ET- 1, TMB - 8, an inhibitor of intracellular stored Ca2+ release, inhibited significantly the transient peak increase, but had no effect on the sustained increase in [Ca2+]i evoked by ET - 1; a buffer solution devoid of Ca2+ had no effect on the transient peak but abolished completely the sustained increase in [ Ca2+]i evoked by ET- 1. These findings indicated that the transient peak increase in [Ca2+]i evoked by Et- 1 was mediated by release of intracellular store of Ca2+ and the sustained increase in [Ca2+]i was caused by extracellular Ca2+ influx.