NaCl flux in the flounder (Pseudopleuronectes americanus) intestine: effects of pH and transport inhibitors.
1. The effects of extracellular pH on Na+ and Cl- absorption were studied in vitro in the small intestine of the winter flounder, Pseudopleuronectes americanus. 2. Reductions in bathing solution pH inhibited JNams (mucosal-to-serosal flux) and JNanet (net flux) (r = 0.90) and JClnet (r = 0.92) [due to an increase in JClsm (serosal-to-mucosal)] and decreased short circuit current (Isc). 3. Luminal bumetanide (0.1 mM) and amiloride (1 mM) inhibited Na+ and Cl- absorption by reducing Jms. 4. Luminal barium (5 mM) and luminal copper (100 microM) decreased JClms and increased JClsm. 5. We conclude that reductions in extracellular pH inhibit a luminal membrane NaCl absorptive process (Na(+)-K(+)-2Cl-) and stimulate an electrogenic Cl- secretory process.
Charney
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AN
Mount Desert Island Biological Laboratory, Salsbury Cove, ME 04672.
Kohlbrecher
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A
Pelkonen
A M
AM
D000584:Amiloride / Q000494:pharmacology; D000818:Animals; D001464:Barium / Q000494:pharmacology; D001692:Biological Transport / Q000187:drug effects; D002034:Bumetanide / Q000494:pharmacology; D003300:Copper / Q000494:pharmacology; D005432:Flounder / Q000378:metabolism*; D006863:Hydrogen-Ion Concentration; D007413:Intestinal Mucosa / Q000187:drug effects / Q000378:metabolism; D007421:Intestine, Small / Q000378:metabolism*; D012965:Sodium Chloride / Q000378:metabolism*; D012979:Sodium Radioisotopes
D012979:Sodium Radioisotopes; D002034:Bumetanide; D001464:Barium; D012965:Sodium Chloride; D003300:Copper; D000584:Amiloride