SITS-sensitive basolateral anion current in rabbit proximal convoluted tubules.
To assess the presence and nature of steady-state anion current across the basolateral membrane in in vitro rabbit proximal convoluted tubules bathed and perfused with a high-chloride, low-bicarbonate solution simulating late proximal tubular fluid, steady-state basolateral cell membrane potential difference (Vb1) was measured by conventional microelectrodes. The mean value of Vb1 was -52 mV. Addition of 1 mM 4-acetamido-4'-isothiocyanostilbene-2,2'-disulfonic acid (SITS) to the bath solution hyperpolarized Vb1 by 30 mV, suggesting the presence of basolateral anion current. Total chloride removal did not change Vb1 significantly, and formate, a presumptive stimulant of electroneutral sodium chloride transport, depolarized Vb1 both in the presence and absence of chloride, suggesting that the formate-stimulated change in Vb1 was chloride independent. In the total absence of chloride and bicarbonate, 1 mM bath SITS and 0.1 mM lumen and bath acetazolamide hyperpolarized Vb1 by 27-35 and 23 mV, respectively. These results suggest that the SITS-sensitive change in Vb1 is independent of chloride and associated with a basolateral anion current that is predominantly due to bicarbonate exit. In the absence of exogenous CO2, cell-to-bath HCO3-dependent anion current can be derived from metabolic CO2.
Kuwahara
M
M
Department of Physiology, University of California, San Francisco 94143-0532.
Rector
F C
FC
Berry
C A
CA
D012856:4-Acetamido-4'-isothiocyanatostilbene-2,2'-disulfonic Acid / Q000494:pharmacology*; D000086:Acetazolamide / Q000494:pharmacology; D000818:Animals; D000838:Anions; D001639:Bicarbonates / Q000494:pharmacology; D002462:Cell Membrane / Q000187:drug effects / Q000502:physiology; D002712:Chlorides / Q000494:pharmacology; D004848:Epithelium / Q000502:physiology; D066298:In Vitro Techniques; D007473:Ion Channels / Q000187:drug effects / Q000502:physiology*; D007687:Kidney Tubules, Proximal / Q000187:drug effects / Q000502:physiology*; D008564:Membrane Potentials; D008954:Models, Biological; D011817:Rabbits; D013267:Stilbenes / Q000494:pharmacology*
D000838:Anions; D001639:Bicarbonates; D002712:Chlorides; D007473:Ion Channels; D013267:Stilbenes; D012856:4-Acetamido-4'-isothiocyanatostilbene-2,2'-disulfonic Acid; D000086:Acetazolamide