Pancreatic exocrine secretion in response to intraduodenal infusion of different detergent agents in anesthetized...

Bile salts, when instilled into the intestine at pH 6, stimulate pancreatic exocrine secretion in man and cat. We investigated if the surface tension as a major physicochemical property of bile acids might be responsible for this effect. In anesthetized cats, either conjugated taurocholate (TC) or unconjugated ursodesoxycholate (UDC) as steroidal detergents or oleate as nonsteroidal detergent were perfused into the duodenum. The critical micellar concentration (CMC) and the surface tension (gamma) were as follows: for oleate 18.6 mmol/l and 27.7 dyn . cm-1, for UDC 10.75 mmol/l and 46.5 dyn . cm-1, for TC 14.5 mmol/l and 58.6 dyn . cm-1. The intraduodenal perfusion of the three solutions at 30 mmol/l and pH 8 evoked an equal pancreatic flow (about 300 mg/15 min) and bicarbonate secretion. It is suggested that the free ionized form of TC perfused intraduodenally is responsible for stimulation of the pancreatic exocrine secretion. We show that the stimulatory effect seems to be independent of the detergency of these molecules.