Effect of theophylline on glucagon and secretin stimulated bile flow

This experiment was performed to determine the effect of theophylline on glucagon and secretin stimulated bile flow. We intended to determine the effect of theophylline, a proposed stimulant of canalicular bile flow, on the bile flow response produced by well-recognized stimulants of canalicular (glucagon) and ductular (secretin) bile flow. Dogs with chronic bile fistulas were used. Dose-response curves for glucagon and secretin were produced by administration of a wide range of glucagon and secretin doses. The effect of 20 mg/kg/hr theophylline on the dose-response curves was determined. Theophylline significantly increased the bile flow and bile electrolyte changes produced by glucagon at low doses but not at maximal doses of glucagon for stimulation of bile flow. Theophylline significantly increased bile volume and bile electrolyte changes at all doses of secretin, including maximal doses. These results suggest that theophylline and glucagon, both purported to be stimulants of canalicular bile flow in dogs, utilize the same receptor mechanism to stimulate bile flow. The effects of secretin, a proposed ductular stimulant, are potentiated by theophylline. On a functional basis, it is possible that there are separate canalicular and ductular loci of hormone action in stimulation of bile secretion.