Regulation of intracellular ph in avian renal proximal tubules.
Kim, Yung Kyu, Olga H. Brokl, and William H. Dantzler.
Department of Physiology, College of Medicine, University of
Arizona, Tucson, Arizona 85724-5051
APStracts 3:0275R, 1996.
In proximal tubules isolated from chicken transitional nephrons,
intracellular pH (pHi), measured with the pH-sensitive fluorescent
dye 2_, 7_-bis(2-carboxyethyl)-5,6-carboxyfluorescein (BCECF), was
about 7.3-7.4 under control conditions [N-2-hydroxyethylpiperazine
-N_-2-ethanesulfonic acid (HEPES)-buffered medium with pH 7.4 at 39
degrees C] and was reduced to about 6.8 in response to NH4Cl pulse.
The rate of recovery of pHi (dpHi/dt) from this acid level to the
resting level and the resting pHi were 1) significantly reduced by
the removal of Na+ from the bath, 2) significantly increased by the
removal of Cl- from the bath, and 3) unchanged by the removal of both
Na+ and Cl- from the bath. The addition of either amiloride or 4,4_
-diisothiocyanostilbene-2,2_-disulfonate (DIDS) to the bath reduced
dpHi/dt to about the same extent as the removal of Na+. These data
suggest that both Na+-coupled and Cl--coupled acid-base fluxes at the
basolateral membrane are involved in determining the resting pHi and
the rate of recovery of pHi after acidification. The most likely
possibilities appear to be a basolateral Na+/H+ exchanger, a
basolateral Na+-coupled Cl-/HCO3- exchanger, a basolateral Na+-HCO3-
-CO32- cotransporter, and a basolateral Na+-independent Cl-/HCO3-
exchanger.
Received 19 April 1996; accepted in final form 26 June 1996.
APS Manuscript Number R224-6.
Article publication pending Am. J. Physiol. (Regulatory Integrative
Comp. Physiology).
ISSN 1080-4757 Copyright 1996 The American Physiological Society.
Published in APStracts on 25 July 1996