Inhibition by propranolol of bile acid- and PGE1-stimulated camp and intestinal secretion

Three colonic and three ileal loops were prepared in six rabbits pretreated with propranolol (PR) 4 mg./kg. I.V. and in five untreated rabbits. In random order, 1 ml. of either deoxycholic acid (DCA) 6 mM., prostaglandin E1 (PGE1) 20 microgram./ml., or saline was placed in each colonic loop and 1 ml. of either cholera enterotoxin (CE) 10 microgram./ml., PGE1 20 microgram./ml., or saline was placed in each ileal loop. In untreated animals, DCA and PGE1 in the colon and CE and PGE1 in the ileum stimulated (P less than 0.01) adenylate cyclase (AC) and net secretion. In the colon, PR abolished DCA-stimulation of AC and net secretion and decreased PGE1-stimulated AC (P less than 0.01) and net secretion. In conclusion, at the doses and times studied, colonic-AC and net secretion stimulated by PGE1 or DCA was distinguished from small bowel-AC and net secretion stimulated by PGE1 or CE.