COMPARISON BETWEEN PHYSIOLOGICAL AND ERYTHROMYCIN-INDUCED INTERDIGESTIVE MOTILITY

Background: The last part of duodenal phase III of the migrating motor complex behaves as a retroperistaltic pump. We have compared the phase-III-like gastroduodenojejunal activity induced by erythromycin with the naturally occurring phase III, focusing on peristaltic patterns. The effect of two doses of erythromycin, 3 mg/kg/h and 12 mg/kg/h (in four subjects), or saline, given intravenously for 15 min, was studied in nine fasting healthy subjects (five men and four women). Methods: Motility was recorded on three different days. On one day standard 5-h eight-channel antroduodenojejunal manometry was performed and saline infused 30 min after the first phase III. On the other two study days, erythromycin in the low or the high dose was infused and recording performed for another 2-h period. Results: The low dose of erythromycin induced a phase III in the stomach in all subjects within 12.8 +/- 1.4 min. In contrast, the higher dose did not induce phase-III activity within the 1st h after infusion but induced marked antral pressure waves. The duration of the erythromycin-induced phase III and the naturally occurring antral phase III was 4.7 +/- 1.7 and 1.9 +/- 0.3 min, respectively (p < 0.01). The duration of the erythromycin-induced phase III in the proximal jejunum was 44% shorter than the spontaneous one (p < 0.01). The propagation velocity, from the proximal duodenum to the proximal jejunum, of the erythromycin-induced phase III was slower than that of the spontaneous phase III: 5.7 +/- 0.9 and 15.9 +/- 3.9 cm/min, respectively (p < 0.01). In the proximal duodenum the proportion of retrograde pressure waves (of all propagating waves) was about 10% in early phase III, increasing to about 85% in late phase III in both the spontaneous and erythromycin-induced phase III. In the proximal jejunum retrograde pressure waves were not observed in phase III. Conclusions: Erythromycin given in a low dose is very effective in inducing phase-III-like motility. The last pail of duodenal phase III is characterized by retroperistalsis also when this motility phase is induced by erythromycin.