title: Autoradiographic localization of tritiated ouabain-sensitive sodium pump sites in ion transporting epithelia.
abstract: The freeze-dry autoradiographic method devised originally by Stirling (J Cell Biol 53:704, 1972) to localize Na+ pump sites with (3H)ouabain is reviewed. Biochemical, physiological, and autoradiographic data are discussed which establish that ouabain binding to intact tissue conforms to rigid criteria for high Na+ pump specificity. Among these are that glycoside binding exhibits saturation kinetics, ligand dependence, and close correlation with degrees of inhibition of Na+-K+-ATPase and Na+ transport. Moreover, localization of Na+ pump sites by this technique shows a cell and membrane specificity which mirrors that obtained by cytochemical and immunocytochemical methods. In addition to resolving cell-specific patterns of localization in heterogeneous tissues, the demonstration of Na+-K+-ATPase by these techniques indicates that Na+ pumps are distributed uniformly along plasmalemmal surfaces and are restricted to the basolateral interface in reabsorptive and secretory epithelia despite the opposing polarity of net transepithelial electrolyte transport.
mesh_terms: D000818:Animals; D001345:Autoradiography; D001693:Biological Transport, Active; D004848:Epithelium / Q000201:enzymology*; D006651:Histocytochemistry; D010042:Ouabain / Q000494:pharmacology*; D012964:Sodium / Q000378:metabolism*; D000254:Sodium-Potassium-Exchanging ATPase / Q000378:metabolism*; D014316:Tritium
chemical_list: D014316:Tritium; D010042:Ouabain; D012964:Sodium; D000254:Sodium-Potassium-Exchanging ATPase