In-vitro effect of pirenzepine on motility of canine gall-bladder.

The action of pirenzepine as an antimuscarinic drug has been investigated on motor responses of muscle strips in the canine gall-bladder. Pirenzepine was further used to examine whether gall-bladder motor responses to synthetic sulphated cholecystokinin octapeptide (CCK-8) are sensitive to pirenzepine. Pirenzepine (10(-9)-10(-5) M) antagonized muscle contractions in response to acetylcholine (10(-9)-10(-2) M) and CCK-8 (10(-11)-10(-6) M) in a significant manner. These findings indicate that pirenzepine is a potent antagonist of two substances that are the principal contractile mediators of gall-bladder contraction and suggest that long-term administration of pirenzepine could contribute to stasis of the gall-bladder.