L-687,306: a functionally selective and potent muscarinic M1 receptor agonist.

The oxadiazole L-687,306 is a high affinity muscarinic agonist with a N-methylscopolamine/oxotremorine-M binding profile predictive of a partial agonist. L-687,306 showed marked selectivity in functional pharmacological assays. L-687,306 was a partial agonist at muscarinic M1 receptors in the rat ganglion but a high affinity competitive antagonist at guinea-pig cardiac M2 and ileal M3 muscarinic receptors. This compound gives an opportunity to study receptor reserve involved in muscarinic receptors in vitro and in vivo.