title: An in vitro inhibitor of Na-K-ATPase present in an adenosinetriphosphate preparation.
abstract: An in vitro inhibitor of Na-K-ATPase was discovered in a commonly used preparation of ATP made by the Sigma Chemical Company, St. Louis, Mo. (Sigma grade ATP). As measured by a reliable and widely used assay system in which phosphate liberation in measured colorimetrically, Na-K-ATPase activity in the rat kidney, small intestine and colon was about 50% lower then Sigma grade ATP was used as substrate as compared to another Sigma Chemical Company product II ATP. Mg-ATPase and adenylate cyclase assays were unaffected by substituting Sigma grade for grade II ATP. The inhibitor of Na-K-ATPase could not be identified. Sigma grade ATP probably should not be used when measuring the activity of Na-K-ATPase in the rat kidney, small intestine, or colon.
mesh_terms: D000251:Adenosine Triphosphatases / Q000032:analysis; D000255:Adenosine Triphosphate / Q000592:standards*; D000818:Animals; D002855:Chromatography, Thin Layer; D003106:Colon / Q000201:enzymology; D003124:Colorimetry; D007202:Indicators and Reagents / Q000592:standards*; D007421:Intestine, Small / Q000201:enzymology; D007668:Kidney / Q000201:enzymology; D008297:Male; D011188:Potassium; D051381:Rats; D012964:Sodium
chemical_list: D007202:Indicators and Reagents; D000255:Adenosine Triphosphate; D012964:Sodium; D000251:Adenosine Triphosphatases; D011188:Potassium