Volume regulation in nih3t3 fibroblasts not expressing p
-glycoprotein. ii. chloride and amino acid fluxes.
Mor[acute]an, J., D. Miranda, C. Pe[tilde]na-Segura, and H. Pasantes
-Morales.
Institute of Cell Physiology, National University of Mexico, Mexico
City, Mexico
APStracts 3:0350C, 1996.
The osmolyte function of amino acids and Cl in native NIH3T3 cells not
expressing the P-glycoprotein (PG) was examined investigating the
free amino acid concentration and the swelling activated efflux of
[3H]taurine, as representative of amino acids, and of 125I as tracer
for Cl. Taurine and 125I efflux was activated by 20% and 30%
hyposmotic solutions. At 50% hyposmotic solutions the osmolyte pool
was essentially depleted. The Cl channel blockers NPPB, DDF,
dipyridamole and niflumic acid inhibited the release of the two
osmolytes by 80-95%. DIDS (400 [mu]M) decreased taurine efflux 80%
without affecting that of 125I. Linolenic and arachidonic acids (5-20
[mu]M) showed a concentration-dependent inhibitory effect on taurine
and 125I fluxes. Omission of Ca decreased osmolyte fluxes by 16%.
Verapamil inhibited the osmolyte release only at 500 [mu]M.
Nimodipine, 25 and 50 [mu]M, decreased the release of [3H]taurine and
125I by about 60 and 80%, respectively, but this effect was
independent of the presence of extracellular Ca. These results
indicate that amino acids and Cl function as osmolytes during RVD in
native NIH3T3 cells.
Received 16 April 1996; accepted in final form 11 October 1996.
APS Manuscript Number C208-6.
Article publication pending Am. J. Physiol. (Cell Physiology).
ISSN 1080-4757 Copyright 1996 The American Physiological Society.
Published in APStracts on 13 November 1996