Effect of vasoactive intestinal polypeptide on basal and cholecystokinin-induced gallbladder pressure.

Studies were conducted in vivo to examine the pressure response of the opossum gallbladder to vasoactive intestinal polypeptide (VIP) alone and in combination with cholecystokinin (CCK). The following observations were made (1) VIP alone produced dose-related decreases in basal gallbladder pressure; (2) VIP eliminated spontaneous contractile activity when present; (3) VIP significantly antagonized the expected pressure response to CCK infusion. These observations lend further support to our proposal that the regulation of gallbladder motor function depends upon the actions and interactions of the gastrointestinal hormones on gallbladder smooth muscle.