Lussier B T, Moor B C, French M B, Kraicer J
Department of Physiology, University of Western Ontario, London, Canada.
Can J Physiol Pharmacol. 1988 Nov;66(11):1373-80. doi: 10.1139/y88-225.
We examined the effect of the voltage-sensitive Ca2+ channel antagonists, diltiazem and nifedipine, on basal and stimulated growth hormone (GH) release from purified somatotrophs. Our aim was to ascertain whether an influx of Ca2+ from the extracellular to the intracellular compartment is essential for augmented release. Basal release was decreased in a concentration-dependent manner by both diltiazem and nifedipine, while cAMP accumulation was unaffected. The release of GH induced by 29 mM K+ was blocked by diltiazem and nifedipine, at 10(-7) and 10(-8) M, respectively. Again cAMP was unaffected. The release of GH induced by growth hormone-releasing factor was significantly reduced by 10(-4) M diltiazem and completely blocked by nifedipine at a concentration of 10(-6) M or greater. Where the antagonists were effective, the growth hormone-releasing factor induced increase in cAMP accumulation was augmented. We conclude that an influx of Ca2+ from the extracellular compartment is essential for stimulated GH release.
我们研究了电压敏感性钙离子通道拮抗剂地尔硫䓬和硝苯地平对纯化的生长激素细胞基础及刺激状态下生长激素（GH）释放的影响。我们的目的是确定细胞外钙离子内流对于增强释放是否至关重要。地尔硫䓬和硝苯地平均以浓度依赖的方式降低基础释放，而环磷酸腺苷（cAMP）积累不受影响。29 mM钾离子诱导的GH释放分别被10⁻⁷ M和10⁻⁸ M的地尔硫䓬和硝苯地平阻断。同样，cAMP不受影响。生长激素释放因子诱导的GH释放被10⁻⁴ M地尔硫䓬显著降低，并在浓度为10⁻⁶ M或更高时被硝苯地平完全阻断。在拮抗剂有效的情况下，生长激素释放因子诱导的cAMP积累增加。我们得出结论，细胞外钙离子内流对于刺激GH释放至关重要。
