1. A standard duodenal perfusion technique was used to study the effects of luminally perfused sodium taurocholate on basal and stimulated biliary and pancreatic secretion and gastrointestinal hormone release in man.
2. During duodenal perfusion with sodium taurocholate alone, both basal and caerulein/secretin-stimulated bilirubin secretion were suppressed. A successive perfusion with a mixture of the bile salt and essential amino acids in combination overcame the biliary suppression and biliary secretion rose above basal levels. A further increase in bilirubin secretion was not observed in a subsequent perfusion with essential amino acids alone in these studies.
3. No inhibitory effect on basal or caerulein/secretin-stimulated trypsin secretion was observed during the bile salt perfusion; basal trypsin secretion was in fact slightly increased during a prolonged (4 h) perfusion of the bile salt.
4. During bile salt perfusion, basal bicarbonate secretion remained unchanged but caerulein/secretin-stimulated bicarbonate secretion was slightly increased.
5. Plasma levels of pancreatic polypeptide, gastric inhibitory peptide and gastrin did not change significantly during duodenal perfusion with bile salt, but plasma levels of motilin were suppressed.
6. These results support the view that bile salts in the duodenum-5-regulate biliary and pancreatic secretion in man and affect plasma levels of motilin.