THE ROLE OF CALCIUM IN PROLACTIN-RELEASE FROM THE PITUITARY OF A TELEOST FISH INVITRO
THE ROLE OF CALCIUM IN PROLACTIN-RELEASE FROM THE PITUITARY OF A TELEOST FISH INVITRO
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DOI：
10.1210/endo-119-6-2848
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发表时间：
1986-12-01
期刊：
影响因子：
4.8
通讯作者：
PANG, PKT
中科院分区：
文献类型：
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作者：
GRAU, EG;SHIMODA, SK;PANG, PKT
从硬骨鱼罗非鱼（Oreochromis mossambicus）的垂体释放PRL，先前已被证明依赖于钙。然而，钙在分泌过程中的来源和具体作用尚未确定。PRL细胞功能调节因子可能改变钙分布的机制也未明确。在本研究中，在静态孵育期间，将培养基K+浓度升高到去极化浓度（56 mM），在孵育81-20 h期间，与对照水平相比，PRL的累积释放没有变化。在灌注孵育期间，暴露于高浓度K+会短暂刺激（.ltoreq）。10分钟)，然后压抑PRL释放。相反，介质渗透压的降低引起PRL释放的快速升高，并持续2小时或更长时间。钙离子进入阻滞剂D600在10-5 M时抑制K+诱导的PRL释放脉冲。然而，相同的浓度没有改变渗透压降低引起的PRL释放。相比之下，除了钙内流外，CoCl2还能阻断一系列钙介导的过程，从而抑制PRL在渗滤和低渗培养基中静态孵育期间的释放。这些发现表明，虽然罗非鱼垂体PRL分泌是钙依赖的，但钙通过电压调节的质膜通道进入可能不是降低渗透压的先决条件。
The release of PRL from the pituitary of a teleost fish, the tilapia (Oreochromis mossambicus), has been previously shown to be dependent on calcium. However, the source(s) and specific action(s) of calcium in the secretory process have not been identified. Also undefined are the mechanisms by which regulators of PRL cell function may alter calcium distribution. In the present investigation, the elevation of medium K+ concentration during static incubations to a depolarizing concentration (56 mM) produced no change in cumulative PRL release over control levels during the 81-20 h of incubation. During perifusion incubation, exposure to high K+ concentrations briefly stimulated (.ltoreq. 10 min) and then depressed PRL release. In contrast, reduced medium osmotic pressure elicited a rapid elevation in PRL release that was sustained for 2 h or more. D600, a calcium entry blocker, at 10-5 M diminished the K+-induced pulses of PRL release. The same concentration, however, did not alter the release of PRL evoked by reduced osmotic pressure. In contrast, CoCl2, which blocks a range of calcium-mediated processes in addition to calcium influx, suppressed PRL release during perifusion and static incubations in hyposmotic medium. These findings suggest that while PRL secretion from the tilapia pituitary is calcium dependent, calcium entry through voltage-regulated plasmalemma channels may not be a prerequisite to the actions of reduced osmotic pressure.