Effect of motilin on the gastric emptying of glucose and fat in humans

Abstract

The effect of natural motilin on the rate of gastric emptying of 200 ml 25% glucose was studied in seven subjects using a 99mtechnetium tin colloid marker. On the control day the subjects received intravenous saline while on the test day they received a motilin infusion of 0.2 pmol/kg/min. Infusions were blind and given in random order. Thirty minutes after glucose ingestion, 25.5 ± 2% of the isotope had emptied during motilin infusion, compared with 11.0 ± 1.5% with saline (p < 0.005). Plasma motilin concentrations rose from a basal value of 23 ± 5 pM to 57 ± 9 pM during the motilin infusion. The faster emptying rates after motilin were reflected in a faster rise of plasma glucose and insulin. The rate of emptying of 99mtechnetium-labeled double cream (200 ml, 24 g fat) was measured in 5 subjects. The rate of gastric emptying of the cream was unaffected by exogenous motilin. Gel Chromatographic analysis of basal plasmas revealed two immunoreactive motilin peaks. After ingestion of cream during motilin infusion, there was an increase of the second peak but a reduction of the first peak whereas both peaks rose on the control day. Thus low-dose exogenous motilin stimulates the gastric emptying of glucose but not of fat.