Transfer of cl- across the placenta of the anaesthetized rat.
Tulc, Jan, Barbora Tulcov[acute]a, Shahid Husain, and Colin P. Sibley.
Department of Pharmacology, 2nd Faculty of Medicine and Department
of Physiology, 1st Faculty of Medicine, Charles University, Prague,
Czech Republic, and Departments of Child Health & School of
Biological Sciences, University of Manchester, St. Mary's Hospital,
Manchester, M13 OJH, U.K.
APStracts 3:0121R, 1996.
The mechanisms of Cl- transfer across the rat placenta have been
investigated. Clearance from mother to fetus (m-f), across the intact
placenta, of 51Cr-EDTA (paracellular diffusion marker) and 36Cl-,
Kmf, was 1.9+/-0.1 [mu]l min-1 and 37.3+/-4.1 [mu]l min-1,
respectively (mean+/-SE, n=10), the large difference indicating that
most m-f transfer of Cl- is transcellular. The clearance of 36Cl-
across the dually perfused placenta in m-f and fetal-maternal (f-m)
directions was symmetrical and highly sensitive to the anion exchange
inhibitor 4,4'-diisothiocyanatostilbene-2,2' disulfonic acid (0.1
mM). The Kmf of 36Cl- was not inhibited by anoxia and had a low
temperature quotient (Q10 between 32-37 oC was 1.52). The m-f
transfer of Cl- seemed to be fully saturated at physiological
concentrations of Cl-. 36Cl- could be displaced from the transporter
on the maternal side by other anions with the following order of
affinity Cl- nearly equal to NO3- > Br- > lactate-
>> gluconate. It is concluded that most of the Cl- transfer
across the rat placenta is effected by an anion exchanger.
Received 26 May 1995; accepted in final form 20 March 1996.
APS Manuscript Number R311-5.
Article publication pending Am. J. Physiol. (Regulatory Integrative
Comp. Physiology).
ISSN 1080-4757 Copyright 1996 The American Physiological Society.
Published in APStracts on 1 April 96