Mechanisms of sodium and chloride transport across isolated sheep reticulum.
1. 22Na+ and 36Cl- fluxes across isolated reticular epithelium of sheep were measured by using the Ussing-chamber technique. 2. Net NaCl absorption driven by Na(+)-K(+)-ATPase was observed under short-circuit conditions. 3. Evaluation of fluxes measured under voltage-clamp conditions indicated that Na+ absorption is mainly electroneutral. 4. Mucosal application of bumetanide, hydrochlorothiazide, or low dose amiloride (10(-4) M) produced no changes in Na+ transport whereas addition of higher doses of amiloride (> or = 10(-3) M) led to a reduction in net Na+ transport. Short chain fatty acids (SCFA) enhanced the amiloride-sensitive Na+ transport. 5. Alterations of JmsNa induced by inhibitors or by SCFA were always accompanied by qualitatively similar changes of JsmNa. Amiloride-sensitive JsmNa was also decreased at low mucosal Na+ concentration. 6. DIDS, SITS, and nitrate reduced both JmsCl and JsmCl. SCFA did not influence chloride transport. 7. It is concluded that Na+ transport is mediated by Na(+)-H+ exchange and by transport processes operating as Na+ self-exchange. Mucosal-to-serosal chloride transport seems partly to depend on anion exchange systems.
Gäbel
G
G
Institut für Veterinärphysiologie, Freie Universität Berlin, F.R.G.
Vogler
S
S
Martens
H
H
D000086:Acetazolamide / Q000494:pharmacology; D000584:Amiloride / Q000494:pharmacology; D000818:Animals; D001693:Biological Transport, Active / Q000187:drug effects; D002034:Bumetanide / Q000494:pharmacology; D002712:Chlorides / Q000378:metabolism*; D005227:Fatty Acids / Q000502:physiology; D066298:In Vitro Techniques; D008564:Membrane Potentials; D010042:Ouabain / Q000494:pharmacology; D012159:Reticulum / Q000378:metabolism*; D012756:Sheep; D012964:Sodium / Q000378:metabolism*; D000254:Sodium-Potassium-Exchanging ATPase / Q000378:metabolism
D002712:Chlorides; D005227:Fatty Acids; D002034:Bumetanide; D010042:Ouabain; D000584:Amiloride; D012964:Sodium; D000254:Sodium-Potassium-Exchanging ATPase; D000086:Acetazolamide