Effect of glucagon on esophageal motor function

This study evaluates the effect of exogenous glucagon on esophageal motor function in man. Manometric studies were performed using an infused catheter system. Resting lower esophageal sphincter (LES) pressure was monitored before and after intravenous pulse doses of glucagon (1 to 100 mug). The effect of glucagon (0 mug ) on esophageal peristalsis was also studied. Multiple blood samples were taken for determination of glucagon, insulin, and glucose concentration. Glucagon effect on LES pressure was also evaluated after LES stimulation by continuous intravenous infusion and pentagastrin (0.04 mug per kg per min). Glucagon caused a transient significant decrease of LES pressure only at pulse doses (20 and 100 mug) which caused nonphysiological elevation of plasma glucagon levels. The temporal profile of decreased LES pressure correlated closely with maximal blood glucagon levels. Glucagon caused no demonstrable change in esophageal peristalsis. During LES stimulation by pentagastrin, glucagon caused significant transient decreases of LES pressure at doses as low as 1 mug per kg. We conclude that glucagon at sufficient dosage has an inhibitory effect on LES pressure. This inhibitory effect is not mediated through changes in serum insulin or glucose and appears to be pharmacological.