Cardiac glycoside receptor in potassium depletion.
Ouabain binding capacity of cell membranes is directly related to (Na+ + K+)-ATPase activity. The extent of ouabain inhibition of (Na+ + K+)-ATPase is a measure of ouabain receptor sites occupied. Dissociation constants of the ouabain-receptor complexes are identical in all organs in a single species but vary among different species. K+ decreases the association rate constant of the ouabain receptor interaction without altering the dissociation rate constants. Titration of digoxin-inhibited (Na+ + K+)-ATPase from guinea pig heart with digoxin antibodies shows a reversal of the inhibition at lower antibody concentrations in the presence of K+ than in the absence of K+. It is concluded that digitalis intolerance in acute hypokalemia reflects the increased affinity of the cardiac glycoside receptor under these conditions.
D000251:Adenosine Triphosphatases / Q000378:metabolism; D000818:Animals; D001665:Binding Sites / Q000187:drug effects; D001921:Brain / Q000378:metabolism; D002417:Cattle; D002462:Cell Membrane / Q000378:metabolism; D004077:Digoxin / Q000378:metabolism; D004285:Dogs; D004305:Dose-Response Relationship, Drug; D004912:Erythrocytes / Q000378:metabolism; D006168:Guinea Pigs; D007008:Hypokalemia / Q000378:metabolism; D007668:Kidney / Q000378:metabolism; D009206:Myocardium / Q000201:enzymology / Q000378:metabolism* / Q000648:ultrastructure; D010042:Ouabain / Q000378:metabolism*; D011188:Potassium / Q000494:pharmacology*; D011955:Receptors, Drug; D013045:Species Specificity
D011955:Receptors, Drug; D010042:Ouabain; D004077:Digoxin; D000251:Adenosine Triphosphatases; D011188:Potassium