title: The effect of ouabain on the guinea pig ileum longitudinal smooth muscle: 1. ATPase activities in a sarcolemma-enriched fraction prepared with the aid of divalent cation depletion of the intact muscle.
abstract: Depletion of divalent cations before fractionation of the longitudinal muscle of the guinea pig ileum yielded a sarcolemma-enriched microsomal fraction free of mitochondria. A major portion of the ATPase activity in the presence of Mg, Na, and K was due to stimulation by Na alone. A further small stimulation by K was demonstrated only in the presence of an activating factor from the 105 000 X g supernatant. Ouabain inhibited only the K activation and had no effect on the Na-stimulated Mg-ATPase.
mesh_terms: D000251:Adenosine Triphosphatases / Q000037:antagonists & inhibitors / Q000378:metabolism*; D000818:Animals; D002413:Cations, Divalent; D004789:Enzyme Activation / Q000187:drug effects; D006168:Guinea Pigs; D007082:Ileum; D008274:Magnesium / Q000378:metabolism; D008297:Male; D009130:Muscle, Smooth / Q000201:enzymology* / Q000648:ultrastructure; D010042:Ouabain / Q000494:pharmacology*; D011188:Potassium / Q000378:metabolism; D012508:Sarcolemma / Q000201:enzymology; D012964:Sodium / Q000378:metabolism; D013347:Subcellular Fractions / Q000201:enzymology
chemical_list: D002413:Cations, Divalent; D010042:Ouabain; D012964:Sodium; D000251:Adenosine Triphosphatases; D008274:Magnesium; D011188:Potassium