Motor interaction between cimetidine and cholecystokinin-related peptides in the gall bladder

In vitro cimetidine (10(-5) g/ml), an antagonist of H2-histamine receptors, caused an augmentation of the contractile effects of histamine (10(-8) - 10(-6) g/m) and caerulein (10(-10) - 10(-8) g/ml) on isolated guinea-pig gall bladder. Also in vivo pretreatment of anesthetized dogs with cimetidine (3 mg/kg) induced an increase of the motor response of the gall bladder to Boots pancreozymin (0.5-5.0 CHR U/kg). These results confirm the existence of relaxing effect of H2 -- receptors in musculature of the gall bladder which can modify the contractile action of cholecystokinin-related peptides.