Electrophysiology of succinate transport across rabbit renal brush border membranes.

Publisher Website
Google Scholar
Abstract
In rabbit renal brush border membrane vesicles, the membrane potential was monitored using a voltage-sensitive optical probe (diS-C3-(5)). The ionic dependence of the electrogenic Na+/succinate cotransporter was determined in the presence of monovalent anions and mono-, di- and trivalent cations. Na+ and La3+ were the only cations capable of supporting a succinate-dependent membrane depolarization: Li+, K+, Rb+, Cs+, NH4+, Hg2+, Ca2+, Ba2+, Sr2+, Mg2+, Cu2+, Fe2+, Cd2+, Be2+, Pb2+, Zn2+, Mn2+ and Co2+ did not. Succinate increased the Na+ permeability of the brush border membrane in a saturable manner; saturating succinate (3 mM) concentrations increased the Na+/K+ permeability (PNa/PK) ratio from 0.6-2.3. In the presence of Na+, Li+ and Hg2+ inhibit the succinate potential; cis-Li+ inhibition is competitive with an apparent Ki of 2 mM, while trans-Li+ is noncompetitive; cis-Hg2+ decreased the maximal depolarization with an inhibitor constant Ki of 8.mu.M, and this effect was irreversible. Cations having no effect included K+, Rb+, Cs+, NH4+, Ba2+, Ca2+, Mg2+, Sr2+, Cu2+, Fe2+, Cd2+, Co2+, Be2+, Zn2+, Pb2+, Mn2+ and La3+. Apparently, succinate/Na+ cotransport produces a specific increase in the Na+ conductance of renal brush borders.

This publication has 15 references indexed in Scilit: