细胞外钙和钾离子对调节离体鲤脑垂体促性腺激素分泌的影响

EFFECTS OF EXTRACELLULAR CALCIUM AND POTASSIUM ON THE REGULATION OF GONADOTROPIN SECRETION FROM PITUITARY OF COMMON CARP IN VITRO

作者于1990年9月-1991年1月采用离体灌流培育方法对鲤鱼脑垂体促性腺激素的分泌调节进行研究。结果表明，脑垂体基础促性腺激素（GtH）分泌不依赖于细胞外钙离子（Ca2+）；但脉冲式鲑鱼促性腺激素释放激素（sGnRH）刺激的GtH分泌，则依赖于细胞外Ca2+，且细胞外Ca2+的作用至少部分通过电位敏感性Ca2+通道。50mmol／L高浓度钾离子（K+）显著刺激脑垂体基础GtH分泌，K+的作用是依赖于时间和细胞外Ca2+的；高浓度K+对脉冲式sGnRH刺激的GtH分泌没有显著影响。

The effects of extracellular Ca2+ and K+ on the basal and salmon GnRH (sGn-RH)-stimulated gonadotropin (GtH) release from pituitary of the common carp (Cyprinut carpio) were studied by using an in uitro perifusion system for pituitary fragments. The basal GtH release from the common carp's perifused pituitary extracellular Ca2+-independent. The GtH release from the common carp's perifused pituitary in response to 2 min pulses of sGnRH (1, 10, 100n mol/L) was extracellular Ca2+dependent; in the absence of extracellular Ca2+ or the reduction in Ca2+ concentration,the significant decreases in the GtH release responses to sGnRH were observed.Voltagesensitive calcium chaunels (VSCC) and antagonist verapamil (VER) dosedependently and significantly inhibited GtH release responses to 2 min pulses of sGnRH,in a VER was ineffective on the basal GtH secretion. These results indicate that tlie effect of extracellular Ca2+ on the GtH-releasing action of sGnRH is, at least, partially through the action of VSCC. 50 m mol/L K+ significantly stimulated the basal GtH release from the perifused pituitary of the common carp, and the action of K+ was time-and extracellular Ca2+-dependent. Moreover, no significant influence of increaaed concentration of K+ on sGnRH-induced GtH release was observed.