Title

Intestinal bicarbonate secretion in Amphiuma measured by pH stat in vitro: relationship with metabolism and transport of sodium and chloride ions

ISBN or ISSN

0022-3751

Publication Title

The Journal of physiology-London

Volume

314

Issue

May

Publication Date / Copyright Date

May 1981

First Page

429

Last Page

443

DOI Number

10.1113/jphysiol.1981.sp013717

Abstract

1. Isolated Amphiuma small intestine exposed on both surfaces to buffered or unbuffered media generated gradients of pH under short-circuited conditions consistent with secretion of HCO3(-). 2. When unbuffered mucosal medium was maintained at pH 7.4 by addition of acid, alkalinization of the mucosal medium occurred at a rate of 1-2 microequiv/hr cm2 under short-circuit conditions (Isc) and was reduced by anoxia, acetazolamide or removal of CO2. 3. The rate of HCO3(-) secretion (JHCO3(-)) was reduced at a mucosal pH above or below 7.4 and was proportional to serosal HCO3(-). 4. JHCO3(-) was reduced in Na+-free (choline) and Cl-free (SO4(2-) media and after exposure to the stilbene SITS. 5. The difference JHCO3(-)--Isc was consistent with net Cl- absorption. 6. The tissue resistance (Rt) was elevated upon exposure to serosal HCO3(-) and lowered by mucosal HCO3(-). 7. The intestinal mucosa exhibited carbonic anhydrase activity that was sensitive to ethoxazolamide. 8. It is concluded that HCO3(-) secretion is active, influenced by intracellular carbonic anhydrase activity and coupled to Cl- and possibly Na+ absorption.

Disciplines

Anesthesiology

Keywords

Neurosciences & Neurology, Physiology

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Peer Reviewed

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