Picotto G, Vazquez G, Boland R
Departamento de Biolog approximately ía, Bioqu approximately ímica y Farmacia, Universidad Nacional del Sur, San Juan 670, 8000 Bahia Blanca, Argentina.
Biochem J. 1999 Apr 1;339 ( Pt 1)(Pt 1):71-7.
The involvement of the phospholipase C (PLC) pathway in the non-genomic regulation of duodenal cell Ca2+ concentration by 17beta-oestradiol was investigated. The PLC inhibitors neomycin (0.5 mM) and U-73122 (2 microM) suppressed the stimulatory effect of 0.1 nM 17beta-oestradiol on the 45Ca2+ influx into enterocytes isolated from rat duodenum. The hormone (1 pM to 10 nM) increased the formation of 1,2-diacylglycerol in a biphasic pattern, characterized by an early peak at 45 s (+82%) and a later peak at 5 min (+46%). Both PLC inhibitors suppressed the first peak but were unable to block the 17beta-oestradiol effect at 5 min. 17beta-Oestradiol also increased the generation of inositol 1,4,5-trisphosphate within 15 s, with maximal stimulation at 30 s. 17beta-Oestradiol induced a rapid (30 s) and sustained (up to 5 min) increase in the intracellular Ca2+ concentration ([Ca2+]i) of fura 2-loaded enterocytes. The fast rise in [Ca2+]i was specific because other sex steroid hormones were without effect and could be blocked to a great extent by U-73122 (by 86% at 1 min). The effects of 17beta-oestradiol on enterocyte [Ca2+]i were decreased significantly (by 75%) in a Ca2+-free extracellular medium but a pronounced increase in [Ca2+]i was obtained after readmission of Ca2+ to the medium. The latter change was suppressed by 10 microM La3+, whereas nitrendipine (1 microM) and verapamil (10 microM) separately were without effect. The permeability of the 17beta-oestradiol-induced Ca2+ influx pathway to Mn2+ was increased 2.8-fold by treatment with oestrogen. These results suggest the operation of a PLC-dependent store-operated Ca2+ channel mechanism in 17beta-oestradiol regulation of enterocyte extracellular Ca2+ influx.
研究了磷脂酶C（PLC）途径在17β-雌二醇对十二指肠细胞Ca2+浓度的非基因组调节中的作用。PLC抑制剂新霉素（0.5 mM）和U-73122（2 μM）抑制了0.1 nM 17β-雌二醇对从大鼠十二指肠分离的肠上皮细胞45Ca2+内流的刺激作用。该激素（1 pM至10 nM）以双相模式增加1,2-二酰基甘油的形成，其特征是在45秒时出现早期峰值（增加82%），在5分钟时出现后期峰值（增加46%）。两种PLC抑制剂均抑制了第一个峰值，但无法在5分钟时阻断17β-雌二醇的作用。17β-雌二醇还在15秒内增加了肌醇1,4,5-三磷酸的生成，在30秒时达到最大刺激。17β-雌二醇诱导用fura 2加载的肠上皮细胞的细胞内Ca2+浓度（[Ca2+]i）快速（30秒）且持续（长达5分钟）增加。[Ca2+]i的快速升高是特异性的，因为其他性类固醇激素没有作用，并且在很大程度上可被U-73122阻断（在1分钟时被阻断86%）。在无Ca2+的细胞外培养基中，17β-雌二醇对肠上皮细胞[Ca2+]i的作用显著降低（降低75%），但在培养基重新加入Ca2+后，[Ca2+]i出现明显增加。后一种变化被10 μM La3+抑制，而尼群地平（1 μM）和维拉帕米（10 μM）单独作用时没有效果。用雌激素处理后，17β-雌二醇诱导的Ca2+内流途径对Mn2+的通透性增加了2.8倍。这些结果表明，在17β-雌二醇对肠上皮细胞细胞外Ca2+内流的调节中存在一种依赖PLC的储存操纵性Ca2+通道机制。
