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.
This is a preview of subscription content, log in via an institution to check access.
Similar content being viewed by others
Reverences
Ammann D, Lanter F, Steiner RA, Schulthess P, Shijo Y, Simon W (1981) Neutral carrier based hydrogen ion selective microelectrode for extra- and intracellular studies. Anal Chem 53:2267–2269
Aronson PS, Nee J, Suhm MA (1982) Modifier role of internal H+ in activating the Na+-H+ exchanger in renal microvillus membrane vesicles. Nature (Lond) 299:161–163
Boron WF, Boulpaep EL (1983) Intracellular pH regulation in the renal proximal tubule of the salamander. Na-H exchange. J Gen Physiol 81:29–52
Boron WF, Boulpaep EL (1983) Intracellular pH regulation in the renal proximal tubule of the salamander. Basolateral HCO −3 transport. J Gen Physiol 81:53–94
Burckhardt B-Ch, Cassola AC, Frömter E (1984) Electrophysiological analysis of bicarbonate permeation across the peritubular cell membrane of rat kidney proximal tubule. II. Exclusion of HCO −3 -effects on other ion permeabilities and of coupled electroneutral HCO −3 transport. Pflügers Arch 401:43–51
Burckhardt B-Ch, Frömter E (1980) Bicarbonate transport across the peritubular membrane of rat proximal tubule. In: Schulz I, Sachs G, Forte JG, Ullrich KJ (eds) Hydrogen transport in epithelia. Elsevier, Amsterdam, pp 277–285
Burckhardt B-Ch, Sato K, Frömter E (1984) Electrophysiological analysis of bicarbonate permeation across the peritubular cell membrane of rat kidney proximal tubule. I. Basic observations. Pflügers Arch 401:34–42
Cassola AC, Mollenhauer M, Frömter E (1983) The intracellular chloride activity of rat kidney proximal tubular cells. Pflügers Arch 399:259–265
Frömter E (1979) Solute transport across epithelia: what can we learn from micropuncture studies on kidney tubules. J Physiol (Lond) 288:1–31
Frömter E (1984) Viewing the kidney through microelectrodes. Am J Physiol 247:F695-F705
Frömter E, Müller CW, Wick T (1971) Permeability properties of the proximal tubular epithelium of the rat kidney studied with electrophysiological methods. In: Giebisch G (ed) Electrophysiology of epithelia. Schattauer, Stuttgart, pp 119–146
Frömter E, Sato K (1976) Electrical events in active H+/HCO −3 transport across rat kidney proximal tubular epithelium. In: Kasbekar DK, Sachs G, Rehm WS (eds) Gastric hydrogen ion secretion. Dekker, New York, pp 382–403
Guggino WF, London R, Boulpaep EL, Giebisch G (1983) Chloride transport across the basolateral cell membrane of theNecturus proximal tubule: dependence on bicarbonate and sodium. J Membr Biol 71:227–240
Jentsch TJ, Keller SK, Koch M, Wiederholt M (1984) Evidence for coupled transport of bicarbonate and sodium in cultured bovine corneal endothelial cells. J Membr Biol 81:189–204
Jentsch TJ, Matthes H, Keller SK, Wiederholt M (1985) Anion dependence of electrical effects of bicarbonate and sodium on cultured bovine corneal endothelial cells. Pflügers Arch 403:175–185
Jentsch TJ, Stahlknecht TR, Hollwede H, Fischer DG, Keller SK, Wiederholt M (1985) A bicarbonate-dependent process inhibitable by disulfonic stilbenes and a Na+/H+ exchange mediate22Na+ uptake into cultured bovine corneal endothelium. J Biol Chem 260:795–801
Kinne-Saffran E, Beauwens R, Kinne R (1982) An ATP-driven proton pump in brush-border membranes from rat renal cortex. J Membr Biol 64:67–76
Kinsella JL, Aronson PS (1980) Properties of the Na+-H+ exchanger in renal microvillus membrane vesicles. Am J Physiol 238:F461-F469
Matsumura Y, Cohen B, Guggino WB, Giebisch G (1984) Electrical effects of potassium and bicarbonate on proximal tubule cells ofNecturus. J Membr Biol 79:145–152
Murer H, Hopfer U, Kinne R (1976) Sodium/proton antiport in brushborder membrane vesicles isolated from rat small intestine and kidney. Biochem J 154:597–604
Nakhoul NL, Boron WF (1985) Intracellular pH regulation in rabbit proximal straight tubules: dependence on external sodium. Fed Proc 44(6):1898 (abstract)
Sabolic I, Haase W, Burckhardt G (1985) ATP-dependent H+ pump in membrane vesicles from rat kidney cortex. Am J Physiol 248:F835-F844
Steiner RA, Oeme M, Ammann D, Simon W (1979) Neutral carrier sodium ion-selective microelectrode for intracellular studies. Anal Chem 51:351–353
Ullrich KJ, Frömter E, Baumann K (1969) Micropuncture and microanalysis in kidney physiology. In: Passow H, Stämpfli R (eds) Laboratory techniques in membrane biophysics. Springer, Berlin Heidelberg New York, pp 106–109
Yoshitomi K, Frömter E (1984) Cell pH of rat renal proximal tubule in vivo and the conductive nature of peritubular HCO −3 (OH−) exit. Pflügers Arch 402:300–305
Yoshitomi K, Frömter E (1985) How big is the electrochemical potential difference of Na+ across rat renal proximal tubular cell membranes in vivo? Pflügers Arch 405 (Suppl)1:S121-S126
Zeuthen T, Hiam RC, Silver IA (1974) Recording of ion activities in the brain. In: Berman H, Herbert N (eds) Ion selective microelectrode. Plenum Press, New York, pp 145–156
Author information
Authors and Affiliations
Rights and permissions
About this article
Cite this article
Yoshitomi, K., Burckhardt, B.C. & Frömter, E. Rheogenic sodium-bicarbonate cotransport in the peritubular cell membrane of rat renal proximal tubule. Pflugers Arch. 405, 360–366 (1985). https://doi.org/10.1007/BF00595689
Received:
Accepted:
Issue Date:
DOI: https://doi.org/10.1007/BF00595689