title: Active hydrogen excretion and sodium absorption through isolated frog skin.
abstract: The in vitro skin of Rana esculenta was studied in open-circuit conditions. It was shown that when the external face is bathed in a 2-meq solution of NaCl, sodium is absorbed at a significantly higher rate than chloride. The ionic balance is maintained by excretion of hydrogen. With a mucosal solution of 2 meq Na2SO4 the equation relating sodium absorption to proton excretion is JnH+ = (-25 +/- 7) - (0.73 +/- 0.04) JnNa+. The correlation between the two variables is highly significant. Hydrogen excretion obeys saturation kinetics in relation to the sodium concentration of the mucosal solution. Maximum excretion occurs at a sodium concentration of 4 meq. When the mucosal solution is a 115-meq solution of Na2SO4 the net flux of sodium is 2.3 times higher than that of hydrogen. The balance is maintained by absorption of SO42-. The effects of various substances on the Na+ext/H+int exchange were studied. With a mucosal solution of 2 meq Na2SO4 and short-circuit conditions it was shown that the hydrogen excretion is active and nearly the same as in open circuit, the short-circuit current is equal (to within 8%) to the sum of the sodium and hydrogen net fluxes, and the correlation between the movements of the two ions is low. A model relating the active proton excretion with the sodium transport mechanism is proposed.
mesh_terms: D000086:Acetazolamide / Q000494:pharmacology; D000584:Amiloride / Q000494:pharmacology; D000818:Animals; D001001:Anura; D001639:Bicarbonates / Q000494:pharmacology; D001692:Biological Transport / Q000187:drug effects; D002245:Carbon Dioxide / Q000494:pharmacology; D006859:Hydrogen / Q000378:metabolism*; D066298:In Vitro Techniques; D008564:Membrane Potentials / Q000187:drug effects; D010042:Ouabain / Q000494:pharmacology; D011893:Rana esculenta; D012867:Skin / Q000187:drug effects / Q000378:metabolism*; D012964:Sodium / Q000378:metabolism*; D013431:Sulfates / Q000378:metabolism; D014667:Vasopressins / Q000494:pharmacology
chemical_list: D001639:Bicarbonates; D013431:Sulfates; D014667:Vasopressins; D002245:Carbon Dioxide; D010042:Ouabain; D000584:Amiloride; D006859:Hydrogen; D012964:Sodium; D000086:Acetazolamide