title: Distribution of bicarbonate-stimulated ATPase in rat intestinal epithelium.
abstract: This study reports on the distribution of bicarbonate-stimulated ATPase in rat intestinal epithelial cells. Brush-border membranes and basolateral membranes were separated from each other and from mitochondrial and other intracellular membranes by differential and density gradient centrifugation. Bicarbonate-sensitive ATPase activity followed the mitochondrial marker succinic dehydrogenase closely throughout all the centrifugation steps. The low HCO3--ATPase activity in purified brush-border and basolateral plasma membranes could be accounted for quantitatively by the small mitochondrial contamination. Consequently, there are no grounds for postulating that this enzyme has a direct role in H+ or HCO3- transport across the rat small intestine.
mesh_terms: D000251:Adenosine Triphosphatases / Q000378:metabolism*; D000818:Animals; D001639:Bicarbonates / Q000494:pharmacology*; D002462:Cell Membrane / Q000201:enzymology; D007413:Intestinal Mucosa / Q000201:enzymology*; D051381:Rats; D013268:Stimulation, Chemical; D013347:Subcellular Fractions / Q000201:enzymology
chemical_list: D001639:Bicarbonates; D000251:Adenosine Triphosphatases