Trimarchi J R, Liu L, Smith P J, Keefe D L
Laboratory for Reproductive Medicine, Marine Biological Laboratory, Woods Hole, Massachusetts 02543, USA.
Biol Reprod. 2000 Sep;63(3):851-7. doi: 10.1095/biolreprod63.3.851.
Programmed cell death (apoptosis) occurs in nearly all cell types examined, including mammalian oocytes and embryos, where it may underlie some forms of infertility in humans. Although the molecular machinery participating in apoptosis have been intensely investigated, the accompanying physiological changes have not received similar attention. In this study, a novel electrophysiology technique has been employed to monitor real-time perturbations in the physiology of mouse embryos undergoing apoptosis evoked by hydrogen peroxide, diamide, and staurosporine. Despite differences in their mode of action, these agents evoked a similar early change in cellular physiology; namely, a pronounced, transient, potassium efflux through tetraethylammonium-sensitive potassium channels accompanied by cell shrinkage. Mouse zygotes exposed to 200 microM H(2)O(2) exhibited potassium efflux that elevated the potassium concentration of the media surrounding embryos by 1.4 +/- 0.1 microM. Pretreatment with tetraethylammonium inhibited this increase (0.2 +/- 0.1 microM). Our results indicate that potassium efflux through potassium channels and concurrent cell shrinkage are early indicators of cell death in embryos and that noninvasive measurements of potassium pathophysiology may identify embryos undergoing cell death prior to the manifestation of other morphological or molecular hallmarks of cell death.
程序性细胞死亡（凋亡）几乎发生在所有已检测的细胞类型中，包括哺乳动物的卵母细胞和胚胎，而这可能是人类某些形式不孕不育的原因。尽管参与凋亡的分子机制已得到深入研究，但伴随的生理变化却未受到类似的关注。在本研究中，一种新的电生理学技术被用于实时监测过氧化氢、二酰胺和星形孢菌素诱导的小鼠胚胎凋亡过程中的生理扰动。尽管这些试剂的作用方式不同，但它们都引起了细胞生理学上类似的早期变化；即，通过四乙铵敏感钾通道的显著、短暂的钾外流，并伴有细胞收缩。暴露于200微摩尔过氧化氢的小鼠受精卵表现出钾外流，使胚胎周围培养基中的钾浓度升高了1.4±0.1微摩尔。用四乙铵预处理可抑制这种升高（0.2±0.1微摩尔）。我们的结果表明，通过钾通道的钾外流和同时发生的细胞收缩是胚胎细胞死亡的早期指标，并且钾病理生理学的非侵入性测量可能在细胞死亡的其他形态或分子特征出现之前识别出正在经历细胞死亡的胚胎。
