Bicarbonate/chloride exchange and intracellular ph throughout
preimplantation mouse embryo development.
Zhao, Yuyuan, and Jay M. Baltz.
Loeb Medical Research Institute, and Human IVF Laboratory, Ottawa
Civic Hospital, and Departments of Obstetrics and Gynecology
(Reproductive Biology Unit), and Physiology, University of Ottawa,
Ottawa, Ontario K1Y 4E9 Canada
APStracts 3:0138C, 1996.
Bicarbonate/chloride (HCO3-/Cl-) exchanger activity, which regulates
intracellular pH (pHi) in the alkaline range, has been shown to be
present throughout preimplantation mouse embryo development and to be
necessary for embryo viability. We have characterized HCO3-/Cl-
exchange activity and its regulation of pHi throughout
preimplantation development (1-cell, 2-cell, morula, and blastocyst
stages). Embryos at each stage can recover from alkalosis. Recovery
was dependent on external [Cl-], activated by increased pHi, and
inhibited by the anion transport inhibitor DIDS and by external HCO3
-. Dependence of exchanger activity on external [Cl-] and on pHi
remained unchanged during preimplantation development. However, the
IC50 for DIDS inhibition increased significantly (by about 5-fold)
after the 1-cell stage. In addition, HCO3-/Cl- exchange activity
decreased over the course of development, with significantly lower
activity at the morula and blastocyst stages relative to the 1-cell
and 2-cell stages, coinciding with the movement of embryo from the
high pH environment of the oviduct to the lower pH environment of the
uterus.
Received 23 January 1996; accepted in final form 18 April 1996.
APS Manuscript Number C50-6.
Article publication pending Am. J. Physiol. (Cell Physiology).
ISSN 1080-4757 Copyright 1996 The American Physiological Society.
Published in APStracts on 8 May 96