Inhibition of cholecystokinin-induced gallbladder contraction by atropine and pirenzepine in man.

The effect of pirenzepine on cholecystokinin (CCK)-stimulated gallbladder contraction in man was compared with that of atropine. Following pretreatment with atropine, pirenzepine or physiological saline in a random order, 6 healthy male volunteers were infused for 75 min with CCK-octapeptide in doses that are reported to mimic physiological plasma concentrations. Gallbladder volumes were determined by real-time ultrasonography. Pirenzepine inhibited CCK-induced gallbladder volume reduction significantly up to 30 min (p less than 0.01) and the magnitude of this inhibition was similar to that of atropine. The results demonstrate that M1 neural muscarinic receptors are involved in the anticholinergic inhibition of CCK-induced gallbladder contraction in man.