Alila H W, Corradino R A, Hansel W
Department of Physiology, New York State College of Veterinary Medicine, Cornell University, Ithaca 14853.
Endocrinology. 1989 May;124(5):2314-20. doi: 10.1210/endo-124-5-2314.
The effect of LH on the intracellular free Ca2+ concentration ([Ca2+]i) was investigated in highly purified small and large bovine luteal cell populations. Luteal cells were obtained from midcycle corpora lutea dispersed with collagenase and separated by flow cytometry into large and small cells. Resting levels of Ca2+ were higher (P less than 0.05) in the large than small cells [314 +/- 25 nM (n = 5) vs. 186 +/- 13 nM (mean +/- SE; n = 13) for large and small cells, respectively]. LH rapidly increased [Ca2+]i in both small and large cells loaded with the fluorescent Ca2+ probe fura-2. In the small cells, [Ca2+]i was immediately increased 2- to 6-fold (from 176 +/- 8 to 468 +/- 8 nM; n = 5) after adding LH. The LH induced [Ca2+]i rise occurred in two phases: an initial peak due to intracellular Ca2+ mobilization and a secondary rise due to Ca2+ influx from extracellular sources. Preincubation of the small cells with EGTA reduced the initial phase and abolished the secondary rise in [Ca2+]. Both forskolin and 8-bromo-cAMP increased [Ca2+]i in the small cells. In contrast, only a single phase of [Ca2+]i rise was observed in LH-treated large cells, and the response was 1.5- to 2-fold greater than the resting Ca2+ levels [314 +/- 25 vs. 435 +/- 60 nM (n = 4), for resting vs. LH-treated values, respectively]. The addition of both LH and prostaglandin F2 alpha (PGF2 alpha) to the large cells resulted in increases in [Ca2+]i that were greater than those induced by each hormone separately (2.0-fold for LH and 2.7-fold for PGF2 alpha vs. 7- to 9-fold in the presence of both hormones). These findings demonstrate that LH induces rapid increases in intracellular [Ca2+]i that differ in magnitude and profile between the small and large bovine luteal cells. Furthermore, LH and PGF2 alpha interacted to promote increases in [Ca2+]i in the large cells, that were higher than the sum of [Ca2+]i induced by each hormone separately.
在高度纯化的大牛黄体细胞群和小牛黄体细胞群中研究了促黄体生成素（LH）对细胞内游离钙离子浓度（[Ca2+]i）的影响。黄体细胞取自周期中期的黄体，用胶原酶分散后，通过流式细胞术分离成大细胞和小细胞。大细胞中的钙离子静息水平高于小细胞（P<0.05）[大细胞为314±25 nM（n = 5），小细胞为186±13 nM（平均值±标准误；n = 13）]。在加载荧光钙离子探针fura-2的小细胞和大细胞中，LH均能迅速升高[Ca2+]i。在小细胞中，加入LH后，[Ca2+]i立即升高2至6倍（从176±8 nM升至468±8 nM；n = 5）。LH诱导的[Ca2+]i升高分为两个阶段：由于细胞内钙离子动员导致的初始峰值和由于细胞外钙离子内流导致的二次升高。用乙二醇双乙醚二胺四乙酸（EGTA）预孵育小细胞可减少初始阶段，并消除[Ca2+]i的二次升高。福斯可林和8-溴环磷酸腺苷（8-bromo-cAMP）均可使小细胞中的[Ca2+]i升高。相比之下，在LH处理的大细胞中仅观察到[Ca2+]i升高的单一阶段，且该反应比静息钙离子水平高1.5至2倍[静息值与LH处理值分别为314±25 nM和435±60 nM（n = 4）]。向大细胞中同时添加LH和前列腺素F2α（PGF2α）会导致[Ca2+]i升高，且升高幅度大于每种激素单独诱导的升高幅度（LH为2.0倍，PGF2α为2.7倍，而两种激素同时存在时为7至9倍）。这些发现表明，LH可诱导细胞内[Ca2+]i迅速升高，且在大牛黄体细胞和小牛黄体细胞之间，升高的幅度和模式有所不同。此外，LH和PGF2α相互作用，促进大细胞中[Ca2+]i升高，且升高幅度高于每种激素单独诱导的[Ca2+]i升高幅度之和。
