Duodenal osmoconcentration and food intake in pigs after ingestion of hypertonic nutrients

Samples were taken from the duodenum of young pigs via indwelling catheters after ingestion of liquid meals. They had been deprived of feed and water overnight. Samples were taken every minute for 15 min and then at 20, 25, 30, 40, 50, and 60 min. After ingestion of hypertonic glucose solutions, duodenal osmolality rose rapidly to maximal levels within 10-15 min when osmoconcentrations were as follows: for 10% glucose, 480 mosmol/kg H2O; for 20%, 680; and for 40%, 1,200. After 5% glucose, osmolality was about 280 mosmol/kg H2O and did not change appreciably during the hour. Water ingestion caused a fall to 60 mosmol/kg H2O at 3 min and then a slow recovery. Ingestion of glucose-in-milk solutions gave similar but slightly higher values. When the glucose-in-water or -milk solutions were ingested just before a meal of feed pellets, meal size was depressed proportional to glucose concentration.