细胞外Ca2+和K8对鲤鱼脑垂体离体生长激素分泌的影响

EFFECTS OF EXTRACELLULAR CALCIUM AND POTASSIUM ON GROWTH HORMONE SECRETION FROM COMMON CARP PITUITARY IN VITRO

  • 摘要: 采用脑垂体离体灌流孵育系统,研究细胞外 Ca2+和 K8对鲤鱼脑垂体基础的和鲑鱼促性腺激素释放激素(sGnRH)刺激的生长激素(GH)分泌的影响。离体灌流孵育的鲤鱼脑垂体基础 GH分泌和 sGnRH 刺激的 GH 分泌都是细胞外 Ca2+依赖的,缺细胞外 Ca2+存在时,基础 GR分泌显著下降,2分钟脉冲式 sGnRH 刺激的 GH 分泌反应接近消失。Ca2+通道阻滞剂异搏定以剂量依存形式显著抑制基础的和2分钟脉冲式sGnRH 刺激的 GH 分泌,表明细胞外 Ca2+的作用至少部分通过细胞膜电位敏感性 Ca2+通道。50mM K8显著刺激基础GH 分泌,并显著加强高剂量sGnRH 刺激的GH 分泌,且K8的作用是细胞外 Ca2+依赖的。

     

    Abstract: The effects of extracellular Ca2+ and K8 on the basal and salmonGnRH (sGnRH)-stimulated growth hormone (GH) release from pituitary of com-mon carp were studied using an in vitro perifusion system for pituitary fragmen-ts. The basal and sGnRH-stimulated GR secretion from erifused pituitary ofcommon carp were extracellular Ca2+-dependent. In the absence of extracellularCa2+, the significant reduction in the basal GH secretion and almost disappearan-ce in the GH release responses to 2--min pulses of sGnRH (1, 10 and 100nM)were observed. Voltage-sensitive calcium channels (VSCC) antagonist verapam il(VER) significantly inhibited the basal GH release and CH release responses to2- min pulses of sGnRH (1,10 and 100nM) in a dose--dependent manner, indica-ting that the effects of extracellular Ca2+ on the basal and sGnRH-stimulated GHrelease are, at least partially, via the action of VSCC. 50mM K8 significantlystimulated the basal GR release from perifused pituitary of common carp, andmarkedly potentiated the action of pulses of high dose of sGnRH (100nM) on GHsecretion. The effects of elevated K8 were extracellular Ca2+--dependent.

     

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