Heterogeneity of the M1 muscarinic receptor subtype between peripheral lung and cerebral cortex demonstrated by the selective antagonist AF-DX 116.
Recent studies have demonstrated that the majority of muscarinic receptors in rabbit peripheral lung homogenates bind pirenzepine with high affinity (putative M1 subtype). In experiments of AF-DX 116 inhibiting [3H](-)quinuclidinyl benzilate or [3H]pirenzepine, we found similar inhibitory constants for AF-DX 116 binding in rat heart and rabbit peripheral lung that were 4-fold smaller (i.e. of higher affinity) than the inhibitory constant for rat cerebral cortex. This result demonstrates heterogeneity of the M1 muscarinic receptor subtype between peripheral lung and cerebral cortex.
D000818:Animals; D002540:Cerebral Cortex / Q000378:metabolism*; D005260:Female; D007700:Kinetics; D008168:Lung / Q000378:metabolism*; D008297:Male; D010890:Pirenzepine / Q000031:analogs & derivatives* / Q000378:metabolism / Q000494:pharmacology; D011813:Quinuclidinyl Benzilate / Q000378:metabolism; D011817:Rabbits; D011976:Receptors, Muscarinic / Q000187:drug effects / Q000378:metabolism*
D011976:Receptors, Muscarinic; D010890:Pirenzepine; D011813:Quinuclidinyl Benzilate; C048593:otenzepad