Release of motilin after duodenal acidification.

The physiological stimulus leading to motilin release in man has not yet been determined. Six healthy volunteers had 3-minute intraduodenal infusions of acid, alkali, or saline solutions. After infusing acid, plasma-motilin rose by 90% at 4 min and was still significantly raised at 45 min, whereas there was an insignificant fall in plasma-motilin after alkali and no change after saline solution. Release of motilin after duodenal acidification may be an important factor in inhibiting gastric emptying.