High affinity of quinidine for a stereoselective microsomal binding site as determined by a radioreceptor assay.
The techniques of the radioreceptor binding assay were applied to detect stereoselective binding of quinidine and quinine to a site on human liver microsomes. Binding of 3H-dihydroquinidine was 50% inhibited by 20-100 nM quinidine, while its enantiomer quinine did not displace the 3H-ligand at concentrations up to 500 nM. This stereoselectivity agreed with the affinity values measured by functional enzyme assays of cytochrome P450 activity using sparteine or debrisoquine as substrates.
D001667:Binding, Competitive; D006801:Humans; D008862:Microsomes, Liver / Q000378:metabolism*; D008968:Molecular Conformation; D011802:Quinidine / Q000031:analogs & derivatives / Q000378:metabolism*; D011803:Quinine / Q000378:metabolism; D011869:Radioligand Assay
C014486:hydroquinidine; D011803:Quinine; D011802:Quinidine