Regulatory mechanisms governing fluid formation in mouse uterus: Role of endometrial ion channels, transporters and their interactions.

摘要

To understand the regulatory mechanisms underlying electrolytes transport across the endometrium, this study investigated the roles of endometrial ion channels, transporters and their interactions using the techniques of electrophysiology, molecular biology, immunohistochemistry and spectrofluorometry.; The primary culture of endometrial epithelial cells exhibits predominantly Na+ absorption, which is mediated by epithelial Na+ channel (ENaC), under basal condition but becomes predominant Cl − secretion, which is mediated by apical Cl− channels, upon stimulation. Using the short-circuit current technique, the mechanisms governing the switch between the two opposite processes have been demonstrated to be mediated by an interaction between ENaC and at least two types of Cl− channels.; HCO₃− secretion is one of the essential functions of the endometrial epithelium as suggested by high HCO₃ − concentration in the uterine fluid, and its critical role in sperm movement, capacitation and embryo development. The present study has investigated both basolateral and apical mechanisms in mediating HCO ₃− transport.; The present study has also demonstrated the expression and function of three isoforms of Na+/H+ exchanger (NHE) in mouse endometrium using RT-PCR, immunohistochemistry, and spectrofluorimetry. The bilateral distribution of the isoforms suggests that they may play different roles in cellular functions.; To demonstrate the physiological importance of endometrial HCO₃ − secretion, the direct effect of endometrial secreted HCO₃− on sperm function was studied. Using the computer-assisted sperm analysis (CASA), chlortetracycline (CTC) staining and co-culture techniques, the present study has demonstrated that both sperm motility and capacitation depended on HCO₃− secreted by cultured mouse endometrial epithelium. The capacitation and fertilizing ability of mouse sperm co-cultured with defective HCO₃− -secreting CF epithelial cells was significantly lower than that with normal HCO₃− secreting epithelial cells, suggesting that impaired uterine HCO₃− secretion due to defective CFTR may greatly suppress sperm capacitation and subsequent egg fertilization leading to infertility as seen in CF women.; In short, the present study has demonstrated the important roles of uterine epithelial ion channels, transporters and their interaction in regulating uterine fluid formation, which is crucial for various reproductive events occurring in the uterus. The information obtained may provide grounds for development of treatment methods for female infertility (such as in CF) and new strategies for contraception. (Abstract shortened by UMI.)