Evidence that parallel Na+-H+ and Cl--HCO3 -(OH-) antiporters transport NaCl in the proximal tubule

Research output: Chapter in Book/Report/Conference proceedingChapter

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Abstract

The present in vitro microperfusion study examined whether active NaCl transport in the proximal convoluted tubule (PCT) occurs via parallel Na+-H+ and Cl--HCO3 -(OH-) exchangers. PCT were perfused with a high chloride, low-bicarbonate solution simulating late proximal tubular fluid, and were bathed in a similar solution containing 6 g/dl albumin. In this setting the driving forces responsible for passive NaCl transport are eliminated. Addition of 0.1 or 0.5 mM luminal 4-acetamido-4'-isothiocyanostilbene-2,2'-disulfonic acid (SITS), 0.5 mM luminal 4,4'-diisothiocyanostilbene-2,2'-disulfonic acid (DIDS), or 0.1 mM bath ethoxyzolamide, a lipophilic carbonic anhydrase inhibitor, resulted in an approximately 50% reduction in volume absorption. Inhibition of the Na+-H+ antiporter with 1.0 mM luminal amiloride inhibited volume absorption by 50%. The transepithelial potential difference (PD) was no significantly different from zero, consistent with an electroneutral mechanism for active NaCl transport. The effect of a Cl--HCO3 -(OH-) exchanger on acidification was examined in PCT perfused with an ultrafiltrate-like solution and bathed in a serumlike albumin solution. Addition of 0.5 mM DIDS did not significantly decrease volume absorption, demonstrating that luminal DIDS did not result in a nonspecific decrease in solute transport. Luminal DIDS significantly stimulated bicarbonate absorption, consistent with a Na+-H+ antiporter running in parallel with a Cl--HCO3 -(OH-) antiporter, which exchanges luminal Cl- for cellular HCO3 - (or OH-). In conclusion, these data are consistent with parallel Na+-H+ and Cl--HCO3 -(OH-) antiporters mediating neutral active NaCl transport in the PCT.

Original languageEnglish (US)
Title of host publicationAmerican Journal of Physiology - Renal Fluid and Electrolyte Physiology
Volume252
Edition2
StatePublished - 1987

Fingerprint

Antiporters
Active Biological Transport
Chloride-Bicarbonate Antiporters
Sodium-Hydrogen Antiporter
Acids
Bicarbonates
Albumins
Ethoxzolamide
4-Acetamido-4'-isothiocyanatostilbene-2,2'-disulfonic Acid
4,4'-Diisothiocyanostilbene-2,2'-Disulfonic Acid
Carbonic Anhydrase Inhibitors
Amiloride
Baths
Chlorides
hydroxide ion

ASJC Scopus subject areas

  • Medicine(all)

Cite this

Baum, M. (1987). Evidence that parallel Na+-H+ and Cl--HCO3 -(OH-) antiporters transport NaCl in the proximal tubule. In American Journal of Physiology - Renal Fluid and Electrolyte Physiology (2 ed., Vol. 252)

Evidence that parallel Na+-H+ and Cl--HCO3 -(OH-) antiporters transport NaCl in the proximal tubule. / Baum, M.

American Journal of Physiology - Renal Fluid and Electrolyte Physiology. Vol. 252 2. ed. 1987.

Research output: Chapter in Book/Report/Conference proceedingChapter

Baum, M 1987, Evidence that parallel Na+-H+ and Cl--HCO3 -(OH-) antiporters transport NaCl in the proximal tubule. in American Journal of Physiology - Renal Fluid and Electrolyte Physiology. 2 edn, vol. 252.
Baum M. Evidence that parallel Na+-H+ and Cl--HCO3 -(OH-) antiporters transport NaCl in the proximal tubule. In American Journal of Physiology - Renal Fluid and Electrolyte Physiology. 2 ed. Vol. 252. 1987
Baum, M. / Evidence that parallel Na+-H+ and Cl--HCO3 -(OH-) antiporters transport NaCl in the proximal tubule. American Journal of Physiology - Renal Fluid and Electrolyte Physiology. Vol. 252 2. ed. 1987.
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