the binding of this muscarinic antagonist is then determined this procedure allows a determination of the affinity of the test compounds for the central muscarinic antagonist site similarly in the receptor 3 h cis methyldioxalane assay rcmd described more fully by vickroy t w et al journal of pharmacology and experimental therapeutics 229 pages 747 to 755 1984 rat cerebral cortex tissue is treated with radiolabeled cis methyldioxalane a known muscarinic binding site agonist the concentration of test compound required to inhibit 50 of the binding of this muscarinic agonist is then determined this procedure allows a determination of the affinity of the test compound for the central muscarinic agonist site the values for the rqnb and rcmd assay are shown in the table as ic 50 concentrations in the muscarinic induced inositol phosphate accumulation assay mipa human sk n sh cells bearing muscarinic binding sites are incubated with the test compound the production of inositol phosphates is then measured stimulation of inositol phosphate turnover reflects the degree of muscarinic agonist activity of the test compound the concentration of test compound required to produce a response 50 of the maximum is then determined __________________________________________________________________________biological activity of compounds of formula i agonist reversal of sisexample rcmd rqnb response hyperactivitynumbercompound 0 1 u03bcm 1 u03bcm ed sub 50 med mg kg __________________________________________________________________________1 methyl methyl 4 1 pyrrolidinyl 2 14 3 nm 2660 nm 10 0 u03bcm 10butynyl carbamate ethanedioate 1 1 salt 1f methyl methyl 4 1 piperidinyl 2 1570 nm 4990 nmbutynyl carbamate ethanedioate 1 1 salt 1g methyl 4 hexahydro 1h.