Modifying effect of bradykinin on motor activity in the guinea-pig gall bladder.

1. The interaction of bradykinin and cholecystokinin preparations was investigated on the guinea-pig isolated gall bladder. Bradykinin (1-100 ng/ml) induced dose-dependent contractile effects which were considerably smaller than those produced by cholecystokinin octapeptide. Bradykinin in a low concentration (1.0 ng/ml) caused a significant increase of the contraction induced by cholecystokinin octapeptide (P less than 0.001) and natural cholecystokinin-pancreozymin (P less than 0.01), and also augmented the effects of acetylcholine on this preparation. Therefore these effects are probably not specific for cholecystokinin.