Department of Anesthesia Faculty Articles

PubMed Identifier

7304752

Bicarbonate Absorption by in Vitro Amphibian Small Intestine

Publication Title

American Journal of Physiology

Publisher

American Physiological Society

ISSN

0193-1857

Publication Date

11-1-1981

Keywords

Physiology

Abstract

Isolated segments of jejunum from Amphiuma bathed in Cl--free (SO42(-)) media usually generated serosa-negative electrical potentials when HCO3(-) was present in the media. Bidirectional isotope fluxes under short circuit revealed a negligible absorption of Na+ and a residual flux consistent with anion absorption. Acetazolamide (10(-4) M) eliminated the short-circuit current and the residual flux. Segments of jejunum exposed on the mucosal surface to HCO3(-) (pH 7.4) alkalinized the unbuffered serosal fluid at a rate of about 1.1 mueq . h-1 . cm-2, as measured by the pH-stat while clamped at zero transepithelial potential. Acetazolamide, anoxia, and 2,4-dinitrophenol lowered the rate of alkalinization and simultaneously reduced the short-circuit current by an equal amount. Absorption was constant above a [HCO3(-)] of 35 meq/l and uninfluenced by applied transepithelial voltage gradients. HCO3(-) absorption was not reduced after replacement of media Na+ or Cl- but was reduced on addition of ouabain or removal of K+. It is concluded that the jejunum actively absorbs HCO3(-) by an electrogenic process that does not involve Na+-H+ exchange.

DOI

https://doi-org/10.1152/ajpgi.1981.241.5.G389

Volume

241

Issue

5

First Page

G389

Last Page

G396

Funding Information

AM-00367/AM/NIADDK NIH HHS/United States AM-17361/AM/NIADDK NIH HHS/United States AM-26870/AM/NIADDK NIH HHS/United States

PubMed ID

7304752

Disciplines

Anesthesiology

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