the specific binding sites for cardiac glycosides in the human heart have certain properties which make it likely that they are the pharmacological receptors for the therapeutic and toxic actions of digitalis glycosides : they are located in the cell membrane and bind cardioactive steroids reversibly with high affinity : half-maximal receptor binding occurs at approximately 2 nm ( approximately 1.5 ng/ml ) for digoxin ;
C0007158
cardiac glycosides
C0012265
digoxin