Effect of antrectomy and truncal vagotomy on erythromycin induced pancreatic polypeptide secretion.

Erythromycin, a motilin agonist, enhances gastrointestinal motility but also stimulates endogenous pancreatic polypeptide (PP) secretion. We investigated whether the effect of erythromycin on PP release is dependent on (1) prokinetic activity of erythromycin generated from the antrum and (2) the long vagus nerve since erythromycin acts via cholinergic neurons. Erythromycin induced PP secretion was determined in 14 patients with antrectomy (6 patients with Billroth I type anastomosis, 8 patients with Billroth II type anastomosis), in 6 patients with truncal vagotomy and pyloroplasty but without gastric resection and in 8 healthy controls. Plasma PP levels in response to erythromycin (3 mg/kg i.v.) were determined at regular intervals for 180 min. Erythromycin induced a significant increase in plasma PP in the control subjects from 22 +/- 4 pmol/l (basal) to 49 +/- 4 pmol/l at 10 min. In the patients with truncal vagotomy plasma PP secretion after erythromycin was significantly (P < 0.05) increased (peak increment vs. basal: 98 +/- 10 pmol/l vs. 27 +/- 2 pmol/l) and prolonged compared to controls. In the patients with antrectomy no significant increases in plasma PP over basal were observed after erythromycin infusion. It is concluded that erythromycin stimulates PP secretion in healthy controls. The PP response to erythromycin is exaggerated after truncal vagotomy but absent after antrectomy indicating that the antrum is essential for erythromycin induced PP secretion.

Effect of erythromycin on gallbladder emptying in patients with antrectomy or truncal vagotomy.

OBJECTIVES: Erythromycin, a motilin-like agent, stimulates gallbladder contraction in healthy control subjects. Because the action of erythromycin is cholinergic dependent and possibly related to premature phase III migrating motor complex activity in the antrum, we investigated the effect of erythromycin on gallbladder volume in six patients with truncal vagotomy without gastric resection and 14 patients with antrectomy (6 with Billroth I anastomosis, 8 with Billroth II anastomosis), and we compared the results obtained with those in eight healthy controls. In addition, the effect of meal ingestion on gallbladder volume was studied. METHODS: Gallbladder volumes, measured with ultrasonography, were determined every 15 min for 180 min after erythromycin infusion (3 mg/kg i.v.), as well as 30 and 60 min after meal ingestion. RESULTS: Basal gallbladder volumes were not significantly different among the four groups. Erythromycin induced a significant (p < 0.01-0.05) gallbladder contraction of maximal 46 +/- 6% in the controls, 49 +/- 9% in the patients with truncal vagotomy, and 38 +/- 7% in the patients with antrectomy and Billroth I anastomosis. In the patients with antrectomy and Billroth II anastomosis, no significant reduction in gallbladder volume after erythromycin was observed. Meal-induced gallbladder contraction was normal in all patients, including those with Billroth II anastomosis. CONCLUSIONS: These results indicate that neither the long vagus nerve nor the antrum is essential for erythromycin-induced effects on the gallbladder. Because no significant reduction in gallbladder volume in response to erythromycin was observed in the patients with antrectomy and Billroth II anastomosis, we suggest that duodenojejunal anatomical integrity is essential for erythromycin-induced gallbladder contraction.