Evidence for a Role of Splanchnic Somatostatin in the Homeostasis of Ingested Nutrients*

Abstract

Somatostatin was infused via the portal vein at a rate of 50 ng/min in a group of eight conscious dogs beginning 30 min before and continuing for 6 h after the ingestion of an 800-g fat-protein meal. The fasting and postprandial levels of plasma somatostatin-like immunoreactivity (SLI), insulin, glucagon, and triglycerides were compared with those during an intraportal infusion of saline as a control. In both groups, SLI rose significantly within 15 min of the ingestion of the meal, but during somatostatin infusion, mean peripheral vein levels of SLI ranged from 30-85 pg/ml above those of the saline control experiments. The postprandial rise in plasma triglycerides was reduced significantly below the control values at all points between 75-270 min, and this reduction was the result of lowered chylomicron levels. Neither fasting nor postprandial insulin or glucagon levels were significantly reduced by the somatostatin infusion. Intraportally infused somatostain also reduced portal vein xylose levels after an intragastric xylose load. The results are compatible with, but do not prove, a physiological role for somatostatin in the homeostasis of ingested nutrients.