Differences in affinities of muscarinic acetylcholine receptor antagonists for brain and heart receptors.
The affinities of atropine, scopolamine, 3-quinuclidinyl benzilate and twelve analogues of 3-quinuclidinyl benzilate were determined for the muscarinic acetylcholine receptor (m-AChR) using membrane preparations from caudate/putamen. The affinity constants thus obtained were compared with affinities previously reported for the m-AChR obtained from ventricular muscle. The affinities differed significantly for six of the compounds, the largest difference being 16-fold. Neither solubilization nor variation of physiologically significant salts led to a significant change in the affinity of that compound. These results are interpreted as supporting the subclassification of the muscarinic acetylcholine receptor.
D000818:Animals; D001285:Atropine / Q000378:metabolism*; D001667:Binding, Competitive; D001921:Brain / Q000378:metabolism*; D002421:Caudate Nucleus / Q000378:metabolism; D004285:Dogs; D005260:Female; D006352:Heart Ventricles / Q000378:metabolism; D066298:In Vitro Techniques; D007700:Kinetics; D009206:Myocardium / Q000378:metabolism*; D009928:Organ Specificity; D011699:Putamen / Q000378:metabolism; D011812:Quinuclidines / Q000378:metabolism*; D011813:Quinuclidinyl Benzilate / Q000031:analogs & derivatives / Q000378:metabolism*; D011817:Rabbits; D051381:Rats; D011919:Rats, Inbred Strains; D011950:Receptors, Cholinergic / Q000378:metabolism*; D011976:Receptors, Muscarinic / Q000378:metabolism*; D012601:Scopolamine / Q000378:metabolism*; D013045:Species Specificity
D011812:Quinuclidines; D011950:Receptors, Cholinergic; D011976:Receptors, Muscarinic; D011813:Quinuclidinyl Benzilate; D001285:Atropine; D012601:Scopolamine