Effects of ph on basolateral tetraethylammonium transport in snake
renal proximal tubules.
Kim, Yung Kyu, and William H. Dantzler.
Department of Physiology, College of Medicine, University of
Arizona, Tucson, Arizona 85724-5051
APStracts 3:0349R, 1996.
Previous work on snake renal proximal tubules suggested that pH might
influence tetraethylammonium (TEA) transport across the basolateral
membrane. To examine this more directly, we determined the effects of
altering either extracellular pH (pHo) or intracellular pH (pHi) on
TEA uptake and efflux across the basolateral membrane of isolated
snake renal proximal tubules. We found no evidence for trans
-stimulation of either TEA uptake or efflux by H+. Therefore, there
was no evidence for a TEA/H+ exchanger. However, we found evidence
for trans-inhibition of both TEA uptake and efflux as well as for
cis-inhibition of TEA uptake by increasing H+ concentration. H+
concentration appeared to have some type of direct effect on
basolateral transport independent of any effect on membrane
potential. Moreover, there appeared to be an optimal intracellular H+
concentration for entry of TEA into the cells that corresponded to
the one found at the physiological pHi of 7.1. There also appeared to
be an optimal extracellular H+ concentration for efflux of TEA from
the cells that corresponded to the one found at the physiological pHo
of 7.4. The mechanism involved in this relationship is unknown, but
the data support a concept derived from previous studies that TEA
transport across the basolateral membrane is asymmetrical.
Received 11 June 1996; accepted in final form 5 September 1996.
APS Manuscript Number R335-6.
Article publication pending Am. J. Physiol. (Regulatory Integrative
Comp. Physiology).
ISSN 1080-4757 Copyright 1996 The American Physiological Society.
Published in APStracts on 19 September 1996