Lane M, Baltz J M, Bavister B D
Department of Animal Health and Biomedical Sciences, University of Wisconsin, Madison, Wisconsin 53706, USA.
Biol Reprod. 1998 Dec;59(6):1483-90. doi: 10.1095/biolreprod59.6.1483.
This study was an investigation of the mechanisms for the regulation of intracellular pH (pHi) by hamster preimplantation embryos. The resting pH values of hamster embryos were similar at the 1-cell (7. 19 +/- 0.34), 2-cell (7.21 +/- 0.21), and 8-cell (7.22 +/- 0.41) stages. Cleavage-stage hamster embryos alleviated intracellular acidosis by activity of the Na+/H+ antiporter. The rate of recovery from acidosis was similar for embryos at 1-cell, 2-cell, and 8-cell stages. When Na+/H+ antiporter activity was inhibited by either incubation in Na+-free medium or the presence of an inhibitor, pHi was unable to recover to initial levels. Instead, pHi remained acidic. The Na+/H+ antiporter was also found to contribute to baseline pH regulation, as incubation in Na+-free medium resulted in an immediate intracellular acidification. The set point for Na+/H+ antiporter was pH 7.14. There was no evidence at any developmental stage for activity of either Na+-dependent HCO3-/Cl- exchanger or H+-ATPase in the regulation of pHi. Inhibition of the Na+/H+ antiporter by an amiloride derivative significantly reduced the ability of 2-cell embryos to develop in culture when challenged with acidosis, indicating that the Na+/H+ antiporter is an essential regulator of pHi.
本研究旨在探究仓鼠植入前胚胎调节细胞内pH值（pHi）的机制。仓鼠胚胎在1细胞期（7.19±0.34）、2细胞期（7.21±0.21）和8细胞期（7.22±0.41）的静息pH值相似。卵裂期仓鼠胚胎通过Na+/H+逆向转运蛋白的活性来缓解细胞内酸中毒。1细胞期、2细胞期和8细胞期胚胎从酸中毒中恢复的速率相似。当通过在无钠培养基中孵育或加入抑制剂来抑制Na+/H+逆向转运蛋白的活性时，pHi无法恢复到初始水平。相反，pHi仍保持酸性。还发现Na+/H+逆向转运蛋白有助于基线pH调节，因为在无钠培养基中孵育会导致细胞内立即酸化。Na+/H+逆向转运蛋白的设定点为pH 7.14。在任何发育阶段，均未发现Na+依赖性HCO3-/Cl-交换体或H+-ATP酶在调节pHi方面有活性。用氨氯地平衍生物抑制Na+/H+逆向转运蛋白，会显著降低2细胞期胚胎在酸中毒刺激下在培养中发育的能力，这表明Na+/H+逆向转运蛋白是pHi的重要调节因子。
