Anion transport processes in the mammalian superficial proximal straight tubule.
Open Access
- 1 August 1976
- journal article
- research article
- Published by American Society for Clinical Investigation in JCI Insight
- Vol. 58 (2), 500-513
- https://doi.org/10.1172/jci108494
Abstract
The experiments reported in this paper were designed to evaluate some of the characteristics of anion transport processes during fluid absorption from superficial proximal straight tubules isolated from rabbit kidney. We measured net chemical C1- flux during fluid absorption from tubules perfused and bathed with Krebs-Ringer buffers containing 113.6 mM C1-, 10 mM acetate, and 25 mM HCO-/3 at pH 7.4; assessed the effects of carbonic anhydrase inhibitors on net fluid absorption in the presence and absence of CO2; and evaluated the influx and efflux coefficients for [14C]-acetate transport at 37degreesC, at 21degreesC, and in the presence of carbonic anhydrase inhibitors. The experimental data shown that, for this nephron segment, net C1- flux accompanies approximately 27.5% of net Na+ absorption; and net C1- absorption may be accounted for by a passive transport process, primarily diffusional in nature. Fluid absorption in this nephron segment is reduced 40-60% by carbonic anhydrase inhibitors, but only when the tubules are exposed to 95% O2-5% CO2 rather than 100% O2. Thus, it seems probably that approximately half of Na+ absorption in these tubules may be rationalized in terms of a carbonic anhydrase-dependent CO2 hydration process. In addition, there may occur in these isolated proximal tubules an acetazolamide-insensitive moiety of HCO-/3 absorption comparable to that observed for proximal tubules in vivo. Finally, we provide evidence that net efflux of luminal acetate is due to metabolic energy-dependent processes other than CO2 hydration and may, under appropriate conditions, account for approximately one-fourth of net Na+ absorption.This publication has 36 references indexed in Scilit:
- Mechanism of renal hydrogen ion secretionKidney International, 1972
- Physical properties of isolated perfused renal tubules and tubular basement membranesJCI Insight, 1972
- The Influence of the Carbonic Anhydrase Inhibitor, Benzolamide (CL-11,366), on the Reabsorption of Chloride, Sodium, and Bicarbonate in the Proximal Tubule of the RatJCI Insight, 1972
- Route of Passive Ion Permeation in EpitheliaNature New Biology, 1972
- The Mechanism of Bicarbonate Reabsorption in the Proximal and Distal Tubules of the Kidney*JCI Insight, 1965
- A Physical Interpretation of the Phenomenological Coefficients of Membrane PermeabilityThe Journal of general physiology, 1961
- THE ROLE OF PLASMA CO2 TENSION AND CARBONIC ANHYDRASE ACTIVITY IN THE RENAL REABSORPTION OF BICARBONATE*JCI Insight, 1960
- Localization of urine acidification in the mammalian kidneyAmerican Journal of Physiology-Legacy Content, 1960
- Renal Synthesis, Degradation and Active Transport of Aliphatic Acyl Amino AcidsAmerican Journal of Physiology-Legacy Content, 1955
- Studies on Potassium Accumulation by Rabbit Kidney Slices: Effect of Metabolic ActivityAmerican Journal of Physiology-Legacy Content, 1951