Plasma motilin levels in normal subjects and patients with diabetes mellitus and certain other diseases. Fasting levels and responses to food and glucose.

Abstract

Plasma motilin levels were measured by dextran-charcoal radioimmunoassay in normal subjects and in patients with diabetes mellitus and certain other disorders. Fasting plasma motilin in normal subjects determined by a single blood sampling varied considerably within a range of 50 to 545 pg/ml. Repeated blood sampling revealed cyclic fluctuations in plasma motilin during fasting, with a peak appearing between an interval of 100 to 120 min which was accompanied by gastric contraction as determined with a balloon inserted into the stomach. Meal ingestion caused a transient but significant rise in plasma motilin, followed by a progressive decrease with an absence of the secretory episode. On the other hand, plasma motilin levels decreased, without an initial increase, following oral and intravenous glucose loading. Fasting plasma motilin levels were significantly elevated in patients with diabetes mellitus, and chronic liver diseases but within normal limits in patients with acromegaly and hyperthyroidism. Repeated blood samplings showed cyclic fluctuation in plasma motilin levels in diabetic patients. Levels rose after meal ingestion to a peak higher than that in normal subjects and remained higher until 120 min. In summary, 1) fasting plasma motilin levels in normal subjects varied considerably because of cyclic fluctuations, 2) meal ingestion caused a transient rise in plasma motilin, followed by a decrease, whereas glucose administration produced only a decrease, 3) plasma motilin levels were elevated in patients with diabetes mellitus.