AJP - Regulatory, Integrative and Comparative Physiology, Vol 257, Issue 3 542-R549, Copyright © 1989 by American Physiological Society
Decreasing pH of rat embryos and fluids estimated by transplacental distribution of DMO
M. D. Collins, C. A. Duggan, C. M. Schreiner and W. J. Scott Jr
Division of Basic Science Research, Children's Hospital Research Foundation, Cincinnati, Ohio 45229-2899.
Utilizing the transplacental distribution of a weak acid,
5,5-dimethyloxazolidine-2,4-dione (DMO), we have measured the pH of cells
within the rat embryo in vivo on days 11.5-14 of gestation. This is a
period of rapid organogenesis in this species when the cells of many organ
systems begin to change from a proliferative mode into a differentiated
state. We found that intracellular pH of the day 11.5 rat embryo is 7.47
+/- 0.03 and decreases steadily to day 14 at which time it reaches 7.11 +/-
0.03. Because there is a concomitant fall in proliferative rate over this
span of development, we suggest this correlation to be additional evidence
of an association between proliferation and alkalinization of the cell
interior. A number of other compartments including embryo plasma, amniotic
fluid, exocoelomic fluid, and yolk sac have a decreasing concentration of
DMO as development advances, indicative of a steadily declining pH. These
changes could have developmental and pharmacokinetic implications.
