Hertelendy F, Molnár M, Rigó J
Department of Obstetrics and Gynecology, St. Louis University School of Medicine, MO 63104, USA.
Mol Cell Endocrinol. 1995 Apr 28;110(1-2):113-8. doi: 10.1016/0303-7207(95)03523-a.
The objective of this study was to test the hypothesis that, in human myometrial cells (HMC), PGF2 alpha and oxytocin promote the release of arachidonic acid (AA) which, in turn, acts to mobilize intracellular Ca2+. Primary monolayer cultures of HMC were labeled with [3H]arachidonic acid ([3H]AA) to isotopic equilibrium before exposure to PGF2 alpha or oxytocin. Radiolabeled phospholipids were separated on thin layer chromatography and quantitated by scintillation counting. Prostanoids were analyzed by high performance liquid chromatography. Calcium release was quantitated in digitonin-permeabilized myocytes preloaded with 45Ca, in the presence of ATP and ruthenium red. PGF2 alpha (10(-7) M) caused a rapid (peaking at 2 min), and significant (P < 0.01) increase in [3H]AA release that was derived selectively from phosphatidylethanolamine (PE), indicative of phospholipase A2 activation. Oxytocin caused a rapid (30 s) and significant increase in diacylglycerol, concomitant with a drop in phosphoinositides, as well as an increase in [3H]AA and a fall in PE and phosphatidylcholine. Exogenous AA caused a rapid and dose-related efflux of 45Ca2+, which was not inhibited by blockers of AA metabolism, or by heparin that abolished inositol 1,4,5-trisphosphate-induced 45Ca2+ release. It is concluded that PGF2 alpha and oxytocin promote, by different mechanisms, the release of AA, which in turn may amplify their action by enhancing Ca2+ mobilization from the sarcoplasmic reticulum, thereby fulfilling the role of intracellular signaling molecule in human myometrium.
在人子宫肌层细胞（HMC）中，前列腺素F2α（PGF2α）和催产素可促进花生四烯酸（AA）的释放，而花生四烯酸反过来又可促使细胞内钙离子（Ca2+）的动员。在暴露于PGF2α或催产素之前，将HMC的原代单层培养物用[3H]花生四烯酸（[3H]AA）标记至同位素平衡状态。放射性标记的磷脂通过薄层色谱法分离，并通过闪烁计数进行定量分析。前列腺素通过高效液相色谱法进行分析。在存在三磷酸腺苷（ATP）和钌红的情况下，对预先加载了45Ca的洋地黄皂苷通透的心肌细胞中的钙释放进行定量分析。PGF2α（10^-7 M）导致[3H]AA释放迅速增加（在2分钟时达到峰值），且具有显著性（P < 0.01），该释放选择性地来源于磷脂酰乙醇胺（PE），表明磷脂酶A2被激活。催产素导致二酰基甘油迅速增加（30秒）且具有显著性，同时磷脂酰肌醇减少，以及[3H]AA增加，PE和磷脂酰胆碱减少。外源性AA导致45Ca2+迅速且与剂量相关的流出，该流出不受AA代谢阻滞剂或肝素的抑制，肝素可消除肌醇1,4,5-三磷酸诱导的45Ca2+释放。得出的结论是，PGF2α和催产素通过不同机制促进AA的释放，而AA反过来可能通过增强肌浆网的Ca2+动员来放大它们的作用，从而在人子宫肌层中发挥细胞内信号分子的作用。
