title: Phloretin sensitive active urea absorption in frog skin.
abstract: This report presents evidence for urea active absorption by isolated skin of Rana esculenta. One of the supporting factors of such evidence is that at a low concentration the urea influx is five times greater than the outflux, in the absence of a chemical gradient. The transport shows a saturation kinetics with an apparent Km = 1.33 mM and is inhibited by un uncoupling agent (FCCP). 5 x 10(-4) M Phloretin, added to the external side, markedly inhibits inward urea transport, whereas it is ineffective when added to the serosal fluid. This provides evidence for a phloretin-sensitive mechanism located at the external side of the epithelium. Phloretin stimulates the sodium active transport; the possible coupling of urea and sodium movement is analysed.
mesh_terms: D000818:Animals; D001693:Biological Transport, Active / Q000187:drug effects; D066298:In Vitro Techniques; D010693:Phloretin / Q000494:pharmacology*; D011893:Rana esculenta; D012869:Skin Absorption / Q000187:drug effects*; D012964:Sodium / Q000378:metabolism; D014508:Urea / Q000378:metabolism*
chemical_list: D014508:Urea; D012964:Sodium; D010693:Phloretin