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.
Department of Cellular and Molecular Biology, CEA-URA1855 (CNRS), Laboratoire Jean Maetz BP 68, Villefranche/Mer, France.
J
J
Ehrenfeld
D000663:Amphibians / Q000378:metabolism*; D000818:Animals; D001693:Biological Transport, Active; D011522:Protons; D012867:Skin / Q000378:metabolism*; D014508:Urea / Q000378:metabolism*
D011522:Protons; D014508:Urea