Abstract
The affinities of various muscarinic antagonists to human detrusor muscle were determined using radioligand binding techiniques. Saturation experiments with 3H-QNB revealed that there were significant amount of muscarinic cholinergic receptors in human detrusor muscle. Displacement of 3H-QNB binding by various muscarinic subtype selective drugs was studied in the inhibition experiment. Pirenzepine, AFDX-116 and 4-DAMP inhibited the 3H-QNB binding to human detrusor muscle with the Ki values (nM) (mean±S. D., n=6) of 243±62.5, 59.7±15.3 and 2.69±0.96, respectively. These data indicate that M3-selective drug possesses the highest affinity to human detrusor muscle. The Ki values of oxybutynin and tiquizium bromide were similar to those of 4-DAMP, suggesting that these two drugs have strong affinities to human detrusor muscle.
