Choy V J, Watkins W B
J Endocrinol. 1976 Jun;69(3):349-58. doi: 10.1677/joe.0.0690349.
Short-term incubation of human placental tissue in Krebs-Ringer bicarbonate buffered media with various concentrations of K+ and Ca2+ showed a graded response in human placental lactogen (HPL) release at different Ca2+ concentrations, but no effect at increased K+ concentration. Media with high Ca2+ caused an inhibition of release, while Ca2+-free media caused a stimulation in HPL release. High concentrations of Mg2+ inhibited release minimally, while Ba2+ had no effect. There was no change in HPL release of HPL but the significance of this effect is unknown. These results suggest that Ca2+ is not required for HPL secretion from placental tissue. It seems that HPL secretion in vitro does not follow the usual pattern where a physiological stimulus or high K+ concentration causes inward movement of calcium which couples stimulation to secretion.
将人胎盘组织在含有不同浓度钾离子（K⁺）和钙离子（Ca²⁺）的 Krebs - Ringer 碳酸氢盐缓冲培养基中进行短期孵育，结果显示，在不同的钙离子浓度下，人胎盘催乳素（HPL）的释放呈分级反应，但钾离子浓度升高时无影响。高钙离子浓度的培养基会抑制 HPL 的释放，而无钙离子的培养基则会刺激 HPL 的释放。高浓度的镁离子（Mg²⁺）对释放的抑制作用极小，而钡离子（Ba²⁺）则无影响。HPL 的释放没有变化，但其作用的意义尚不清楚。这些结果表明，胎盘组织分泌 HPL 不需要钙离子。体外 HPL 的分泌似乎并不遵循通常的模式，即生理刺激或高钾离子浓度会导致钙离子内流，从而将刺激与分泌联系起来。
