Urinary bladder-selective action of the new antimuscarinic compound vamicamide

1. The inhibitory action of vamicamide (FK176, (±)-(2R * , 4R * )-4-dimethylamino-2-phenyl-2-(2-pyridyl)valeramide, CAS 132373-81-0) on the responses of various tissues to the cholinergic agonists, carbachol and McN-A-343 (4-[m-chlorophenylcarbamoyloxy]-2-butynyl-trimethylammonium chloride, CAS 55-45-8), was investigated in isolated tissue preparations. Vamicamide showed competitive antagonistic actions against all the preparations tested and its pA 2 value for the urinary bladder was 6.82, which was higher than that for the atria (5.94) and almost the same as that for the vas deferens (6.90) and for the stomach (6.81)