Rheogenic sodium-bicarbonate cotransport in the peritubular cell membrane of rat renal proximal tubule
- 1 December 1985
- journal article
- research article
- Published by Springer Nature in Pflügers Archiv - European Journal of Physiology
- Vol. 405 (4), 360-366
- https://doi.org/10.1007/bf00595689
Abstract
The mechanism of bicarbonate transport across the peritubular cell membrane was investigated in rat kidney proximal tubules in situ by measuring cell pH and cell Na+ activity in response to sudden reduction of peritubular Na+ and/or HCO 3 − . The following observations were made: 1. sudden peritubular reduction of either ion concentration produced the same transient depolarizing potential response; 2. bicarbonate efflux in response to peritubular reduction of bicarbonate was accompanied by sodium efflux; 3. sodium efflux in response to peritubular sodium removal was accompanied by cell acidification indicating bicarbonate efflux; 4. all aforementioned phenomena were inhibited by SITS (10−3 mol/l) except for a small SITS-independent sodium efflux and depolarization which occurred in response to peritubular sodium removal and was not accompanied by cell pH changes; 5. bicarbonate efflux and accompanying potential changes in response to reduction of peritubular bicarbonate virtually vanished in sodium-free solutions. From these observations we conclude that bicarbonate efflux proceeds as rheogenic sodium-bicarbonate cotransport with a stoichiometry of bicarbonate to sodium greater than 1. The question which of the charged species of the bicarbonate buffer system moves cannot yet be decided. Attempts to determine the stoichiometry from the SITS-inhibitable initial cell depolarization and from the SITS-inhibitable initial fluxes suggest a stoichiometry of 3 HCO 3 − : 1 Na+. In addition to sodium-dependent bicarbonate flux, evidence was obtained for a sodium-independent transport system of acids or bases which is able to regulate cell pH even in sodium-free solutions.Keywords
This publication has 27 references indexed in Scilit:
- Evidence for coupled transport of bicarbonate and sodium in cultured bovine corneal endothelial cellsThe Journal of Membrane Biology, 1984
- Electrical effects of potassium and bicarbonate on proximal tubule cells ofNecturusThe Journal of Membrane Biology, 1984
- The intracellular chloride activity of rat kidney proximal tubular cellsPflügers Archiv - European Journal of Physiology, 1983
- Chloride transport across the basolateral cell membrane of theNecturus proximal tubule: Dependence on bicarbonate and sodiumThe Journal of Membrane Biology, 1983
- Intracellular pH regulation in the renal proximal tubule of the salamander. Na-H exchange.The Journal of general physiology, 1983
- Intracellular pH regulation in the renal proximal tubule of the salamander. Basolateral HCO3- transport.The Journal of general physiology, 1983
- Modifier role of internal H+ in activating the Na+–H+ exchanger in renal microvillus membrane vesiclesNature, 1982
- An ATP-driven proton pump in brush-border membranes from rat renal cortexThe Journal of Membrane Biology, 1982
- Neutral carrier based hydrogen ion selective microelectrode for extra- and intracellular studiesAnalytical Chemistry, 1981
- Neutral carrier sodium ion-selective microelectrode for intracellular studiesAnalytical Chemistry, 1979