Effect of BM-5, a presynaptic antagonist-postsynaptic agonist, on cortical acetylcholine release

The effect of N-methyl-N-(1-methyl-4-pyrrolidino-2-butynyl) acetamide (BM-5) on acetylcholine release from the cerebral cortex was investigated in unanaesthetized and urethane-anaesthetized rats. BM-5 at doses ranging from 0.3 to 5 mg/kg i.p. enhanced acetylcholine output in both groups of rats. The maximum increase occurred with 0.5 mg/kg in the unanaesthetized and 2 mg/kg in the anaesthetized rats. The effect lasted approximately 60 min. At the largest doses peripheral muscarinic effects including salivation, chromodachryorrhea and rhinorrhea were also seen. These results demonstrate that BM-5 exerts presynaptic antagonistic and postsynaptic agonistic effects on muscarine receptors in vivo also.