Control of gastric emptying in the pig: influence of duodenal infusions of glucose and emulsified fat.

The influence of duodenal infusions of emulsified fat (20% Intralipid) and glucose (40%, w/v) on gastric emptying during the feeding period was studied in five pigs. Gastric emptying was measured by evacuation of gastric contents immediately the pigs had finished feeding in animals fitted with a gastric cannula and a duodenal catheter and fed a solid meal mixed with water. Infusions at various rates of Intralipid and glucose given either from the start of feeding or up to 30 min prior to feeding until the pigs had finished feeding inhibited gastric emptying of dry matter (DM) and liquids in a qualitatively similar but quantitatively different manner. With both infusions the rates of gastric emptying of DM and liquids were progressively reduced with pre-infusions of 0, 10, 20 and 30 min. Slow infusions of Intralipid (2.3 and 4.6 ml/min) inhibited gastric emptying of DM and liquids to a greater extent than equicaloric infusions of glucose (3 and 6 ml/min), but faster infusions of Intralipid (6 ml/min) inhibited emptying less than equicaloric infusions of glucose (8 ml/min). When the DM emptied was converted into digestible energy (DE) there was no evidence that Intralipid inhibited gastric emptying calorically. In contrast the results showed that there was caloric regulation of gastric emptying with infusions of glucose begun at the start of feeding. There was a linear reduction in the rate of DM emptied with increase in the rate of glucose infusion (2-8 ml/min) of 64.5 +/- 4.8 g DM per MJ/min glucose infused, i.e. equivalent to a reduction of 0.98 +/- 0.07 kJ/min DE emptied for each kJ/min glucose infused. These changes in gastric emptying with duodenal infusions of glucose and Intralipid mirror the changes previously observed in food intake following similar infusions, and the results are therefore compatible with control of gastric emptying being an important site of short-term regulation of food intake in the pig.