Effect of substance P on CCK- or VIP-induced choleresis in anesthetized dogs

10 anesthetized dogs were provided with acute common bile duct fistulas and the gallbladder was excluded. Hepatic bile output and biliary content of sodium, potassium and amylase were studied. 6 caval infusions were administered of CCK, 0.3 Ivy U-kg^-1 min^-1, with a superimposed infusion of SP, 20 ng kg^-1 min^-1. 7 caval infusions were given of VIP, 50 ng-kg^-1 min^-1, with a superimposed infusion of SP, 20 ng·kg^-1 min^-1. CCK increased bile output and biliary content of sodium, potassium and amylase by 78–110%. The corresponding increase induced by VIP was 55–85%. Biliary pH was not influenced. SP abolished the effects of both CCK and VIP. It is suggested that all peptides studied influenced canalicular bile secretion by changing the electrolyte excretion.