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Functional role of bicarbonate in propionate transport across guinea‐pig isolated caecum and proximal colon.
Author(s) -
von Engelhardt W,
Gros G,
Burmester M,
Hansen K,
Becker G,
Rechkemmer G
Publication year - 1994
Publication title -
the journal of physiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.802
H-Index - 240
eISSN - 1469-7793
pISSN - 0022-3751
DOI - 10.1113/jphysiol.1994.sp020198
Subject(s) - caecum , propionate , guinea pig , bicarbonate , chemistry , distal colon , proximal colon , sodium bicarbonate , biochemistry , medicine , organic chemistry , colorectal cancer , cancer
1. Unidirectional fluxes of propionate across isolated epithelia from the guinea‐pig caecum and proximal colon were measured under short‐circuit current conditions. In the caecum and proximal colon the serosal‐to‐mucosal propionate flux (JPrsm) was higher than mucosal‐to‐serosal flux (JPrms), resulting in a net secretory flux of propionate. 2. HCO3(‐)‐CO2‐free solution reduced JPrms in the caecum and proximal colon markedly; JPrsm was not (caecum) or little (proximal colon) affected. The subsequent addition of acetazolamide caused a further decrease in JPrms in the proximal colon, but not in the caecum. 3. In HCO3(‐)‐containing solutions acetazolamide or ethoxzolamide inhibited JPrms; JPrsm was not affected. A macromolecular carbonic anhydrase inhibitor, prontosil‐dextran, had no effect on propionate fluxes, indicating that the intracellular carbonic anhydrase is of importance for short‐chain fatty acid transport. 4. Subsequent to carbonic anhydrase inhibition, mucosal addition of amiloride caused a slight further decrease of JPrms in the caecum and proximal colon; JPrsm was not affected. 5. Results support the view that a considerable proportion of short‐chain fatty acids (SCFAs) is absorbed via a SCFA(‐)‐HCO3‐ exchange.