Li M, Asem E K, Tsang B K
Department of Obstetrics and Gynecology, University of Ottawa, Ontario, Canada.
Gen Comp Endocrinol. 1989 Aug;75(2):265-70. doi: 10.1016/0016-6480(89)90079-8.
The importance of extracellular sodium (Nao+) in the progesterone production in hen granulosa cells from the first (F1), second (F2), and third (F3) largest preovulatory follicles was investigated in short term incubations. Progesterone synthesis in the absence or presence of the gonadotropin increased with increasing Nao+ concentration. Luteinizing hormone (LH) caused an additional and significant increase in steroidogenesis at every Nao+ concentration tested. However, no significant difference in the ED50 of Nao+ among F1, F2, and F3 cells was observed whether in the absence or the presence of the gonadotropin. Furthermore, although LH provoked steroidogenesis dose dependently in F1, F2, and F3 granulosa cells, no significant change in the ED50 of LH was observed among F1, F2, and F3 cells. The Na+/H+ exchange inhibitor, amiloride, attenuated both basal and LH-stimulated steroidogenesis in a concentration-dependent manner in the presence of Nao+. Amiloride was ineffective in the absence of Nao+. The present studies indicate the importance of Nao+ in the modulation of steroidogenesis in hen granulosa cells. Since steroidogenesis was suppressed by amiloride only in the presence of sodium, it is suggested that Nao+ is important for the maintenance/regulation of intracellular pH by an exchange with intracellular H+. Our studies also suggest that the sodium modulatory mechanism may not be a determinant in the differential progesterone production observed among the three largest preovulatory follicles.
在短期培养中，研究了细胞外钠（Nao +）在来自第一（F1）、第二（F2）和第三（F3）大的排卵前卵泡的母鸡颗粒细胞孕酮生成中的重要性。在有无促性腺激素的情况下，孕酮合成均随Nao +浓度的增加而增加。在每个测试的Nao +浓度下，促黄体生成素（LH）都会使类固醇生成额外显著增加。然而，无论有无促性腺激素，在F1、F2和F3细胞中均未观察到Nao +的半数有效剂量（ED50）有显著差异。此外，尽管LH在F1、F2和F3颗粒细胞中剂量依赖性地激发类固醇生成，但在F1、F2和F3细胞中未观察到LH的ED50有显著变化。在有Nao +存在的情况下，Na + /H +交换抑制剂阿米洛利以浓度依赖性方式减弱基础和LH刺激的类固醇生成。在没有Nao +的情况下，阿米洛利无效。本研究表明Nao +在调节母鸡颗粒细胞类固醇生成中的重要性。由于仅在有钠存在的情况下阿米洛利才抑制类固醇生成，因此提示Nao +通过与细胞内H +交换对维持/调节细胞内pH很重要。我们的研究还表明，钠调节机制可能不是在三个最大的排卵前卵泡中观察到的孕酮生成差异的决定因素。
