Active proton and urea transport by amphibian skin.
Proton secretion in frog skin is mediated by an electrogenic H+ pump. Pharmacological and immunocytological approaches have identified this pump as belonging to the V-ATPase class. The key role of this V-ATPase in proton secretion (acid-base balance) and as a membrane energizer of other solute transport from very dilute solutions is outlined. It is shown that the frog skin constitutes a model of a V-ATPase-dependent Na+ transport mechanism applicable to other freshwater animals. On the other hand, attempts to implicate the V-ATPase in the active urea transport that develops through the skin of salt-adapted frogs have failed; the nature of the different urea transporters located on apical and basal epithelial cell membranes and those responsible for active urea reabsorption remain to be identified.
Ehrenfeld
J
J
Department of Cellular and Molecular Biology, CEA-URA1855 (CNRS), Laboratoire Jean Maetz BP 68, Villefranche/Mer, France.
D000663:Amphibians / Q000378:metabolism*; D000818:Animals; D001693:Biological Transport, Active; D011522:Protons; D012867:Skin / Q000378:metabolism*; D014508:Urea / Q000378:metabolism*
D011522:Protons; D014508:Urea