Operational modes of the organic anion exchanger in canine renal brush-border membrane vesicles
T. G. Steffens, P. D. Holohan and C. R. Ross Department of Pharmacology, State University of New York Health Science Center, Syracuse 13210. This study delineates the various operational modes catalyzed by the organic anion exchanger present in the canine renal brush-border membrane. The experiments...
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Veröffentlicht in: | American journal of physiology. Renal physiology 1989-04, Vol.256 (4), p.596-F609 |
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Zusammenfassung: | T. G. Steffens, P. D. Holohan and C. R. Ross
Department of Pharmacology, State University of New York Health Science Center, Syracuse 13210.
This study delineates the various operational modes catalyzed by the
organic anion exchanger present in the canine renal brush-border membrane.
The experiments examined the carrier-mediated effects of various organic
and inorganic anions on the transport of either p-[3H]aminohippuric acid
([3H]PAH) or 36Cl-. [3H]PAH countertransport was significantly stimulated
by PAH, urate, Cl-, Br-, HCO3-, and by a pH gradient. This pH stimulation
remained in the absence of HCO3- (i.e., under N2), implying PAH-OH-
exchange. Furosemide, bumetanide, penicillin, and probenecid inhibited
countertransport of [3H]PAH. Likewise, the above anions produced cis
inhibition of [3H]PAH transport. The cis and trans effects of SO4(-2) and
formate were minimal. 36Cl- countertransport was stimulated by PAH, Cl-,
Br-, HCO3-, formate, and by a pH gradient that was effective even in the
absence of HCO3- (i.e., under N2), implying Cl- -OH- exchange. Cl- -OH- and
Cl- -Cl- exchange was inhibited by PAH. In each instance, the
trans-stimulation of 36Cl- efflux was insensitive to maneuvers that created
an inside-positive membrane potential, demonstrating electroneutral
mediated exchange. We conclude that the organic anion transporter can
operate in three distinct exchange modes: organic-organic,
organic-inorganic, and inorganic-inorganic. |
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ISSN: | 0363-6127 0002-9513 1931-857X 2161-1157 1522-1466 |
DOI: | 10.1152/ajprenal.1989.256.4.F596 |