Activation of Cl-/OH- exchange by parachloromercuribenzoic acid in rabbit renal brush-border membranes.
The effect of the sulfhydryl reagent parachloromercuribenzoic acid (PCMB) on chloride transport was examined in rabbit renal brush-border membrane vesicles (BBMV). PCMB had no effect on the chloride conductive pathway. In the presence of an inside-alkaline pH gradient and a K-/valinomycin voltage clamp, the addition of PCMB stimulated 36Cl uptake and induced a threefold overshoot above the equilibrium value, indicating Cl/OH exchange. The effect of PCMB was reversed by dithiothreitol. Cl/OH exchange was not observed in the absence of PCMB. PCMB-activated Cl/OH exchange persisted even when the membrane potential was made inside-negative relative to the controls, thus, demonstrating that PCMB's effect on 36Cl uptake under pH-gradient conditions is not mediated by parallel Cl- and H+ conductive pathways. PCMB-activated Cl/OH exchange was inhibited by 4,4'-diisothiocyanostilbene-2,2'-disulfonic acid (DIDS) and 5-nitro-2-(3-phenylpropylamino)-benzoic acid (NPPB) with IC50 values of 290 and 80 microM, respectively. These results demonstrate that modification of sulfhydryl groups by PCMB activates Cl/OH exchange in BBMV.
Karniski
L P
LP
Department of Internal Medicine, University of Iowa, Iowa City 52242.
D017878:4,4'-Diisothiocyanostilbene-2,2'-Disulfonic Acid; D012856:4-Acetamido-4'-isothiocyanatostilbene-2,2'-disulfonic Acid / Q000031:analogs & derivatives / Q000494:pharmacology; D000818:Animals; D001692:Biological Transport / Q000187:drug effects; D002352:Carrier Proteins / Q000187:drug effects*; D027963:Chloride-Bicarbonate Antiporters; D002712:Chlorides / Q000378:metabolism*; D002729:Chloromercuribenzoates / Q000494:pharmacology*; D006878:Hydroxides / Q000378:metabolism*; D007672:Kidney Cortex / Q000187:drug effects* / Q000378:metabolism / Q000648:ultrastructure; D008297:Male; D008564:Membrane Potentials / Q000187:drug effects; D008871:Microvilli / Q000187:drug effects / Q000378:metabolism; D011817:Rabbits; D020245:p-Chloromercuribenzoic Acid
D002352:Carrier Proteins; D027963:Chloride-Bicarbonate Antiporters; D002712:Chlorides; D002729:Chloromercuribenzoates; D006878:Hydroxides; D012856:4-Acetamido-4'-isothiocyanatostilbene-2,2'-disulfonic Acid; D020245:p-Chloromercuribenzoic Acid; D017878:4,4'-Diisothiocyanostilbene-2,2'-Disulfonic Acid