Coupling of muscarinic receptors to adenylate cyclase in the rabbit myocardium: effects of receptor inactivation.

摘要: The relationship between muscarinic receptor occupancy and adenylate cyclase inhibition was investigated in homogenates of the rabbit myocardium. highly efficacious agonist oxotremorine-M caused half-maximal activity at a concentration (Ki) that 10-fold smaller than required for presence 0.1 mM GTP (D50-GTP) as measured by competitive displacement binding [3H]N-methylscopolamine. In contrast, there much closer agreement Ki D50-GTP less oxotremorine analog BM5 [N-methyl-N-(1-methyl-4-pyrrolidino-2-butynyl)acetamide]. By comparing equal levels before after partial inactivation receptors with benzilycholine mustard, it possible to estimate dissociation constants (KA) analogs. There good KA also degree determined pharmacologyically estimated measurements