Apical membrane of native OMCDi cells has nonselective cation channels

Autor: Jill W. Verlander, Seung-Hyun Noh, Shen-Ling Xia, Charles S. Wingo, Craig H. Gelband
Rok vydání: 2001
Předmět:
Zdroj: American Journal of Physiology-Renal Physiology. 281:F48-F55
ISSN: 1522-1466
1931-857X
DOI: 10.1152/ajprenal.2001.281.1.f48
Popis: The purpose of this study was to examine cation channel activity in the apical membrane of the outer medullary collecting duct of the inner stripe (OMCDi) using the patch-clamp technique. In freshly isolated and lumen-opened rabbit OMCDi, we have observed a single channel conductance of 23.3 ± 0.6 pS ( n = 17) in cell-attached (c/a) patches with high KCl in the bath and in the pipette at room temperature. Channel open probability varied among patches from 0.06 ± 0.01 at −60 mV ( n = 5) to 0.31 ± 0.04 at 60 mV ( n = 6) and consistently increased upon membrane depolarization. In inside-out (i/o) patches with symmetrical KCl solutions, the channel conductance (22.8 ± 0.8 pS; n = 10) was similar as in the c/a configuration. Substitution of the majority of Cl− with gluconate from KCl solution in the pipette and bath did not significantly alter reversal potential ( E rev) or the channel conductance (19.7 ± 1.1 pS in asymmetrical potassium gluconate, n = 4; 21.4 ± 0.5 pS in symmetrical potassium gluconate, n = 3). Experiments with 10-fold lower KCl concentration in bath solution in i/o patches shifted E rev to near the E rev of K+. The estimated permeability of K+ vs. Cl− was over 10, and the conductance was 13.4 ± 0.1 pS ( n = 3). The channel did not discriminate between K+ and Na+, as evidenced by a lack of a shift in the E rev with different K+ and Na+ concentration solutions in i/o patches ( n = 3). The current studies demonstrate the presence of cation channels in the apical membrane of native OMCDicells that could participate in K+ secretion or Na+ absorption.
Databáze: OpenAIRE