Bile acids and colonic motility in the rabbit and the human

Colonic motor activity was initiated by infusions of bile salts into the caecum or rectum of the anaesthetized rabbit. Primary bile acids were examined proximally and distally in the colon and elicited marked motor responses. Sinc dihydroxy bile acids are known to be potent inhibitors of electrolyte and water absorption in the colon, the secondary bile acid deoxycholic acid, the dihydroxyl compound most related to cholic acid which is the main bile acid in the rabbit, was examined distally and was also active, but to a lesser extent than cholic acid conjugates in this species. In man, a relationship was found between the faecal bile acid excretion and colonic motility: the introduction of bile acids directly into the human sigmoid colon and rectum also stimulated colonic motility. In man, the dihydroxy compound chenodeoxycholic acid was slightly more active than conjugates of cholic acid.