Relationships Between Gastric Emptying and Intestinal Absorption of Nutrients and Energy in Mini Pigs
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Little is known about the relationship betweengastric emptying of nutrients regulated by feedbackmechanisms and the absorptive capacity of the gut.Therefore, we wanted to elucidate theseinterrelationships. A 150-cm jejunal segment was perfused (1-8kcal/min) with three different nutrient solutions(either 60% of energy as carbohydrate, or 60% asprotein, or 33.3% of each nutrient). In separateexperiments, gastric emptying was measured afteradministration of three different meals with the samenutrient composition as the perfusion solutions. Thejejunal absorption of carbohydrate, protein, fat, andenergy demonstrated saturation kinetics. The kineticsdiffered among the three nutrients; carbohydrates wereabsorbed at higher rates than fat and protein.Interactions among the nutrients altered the kinetics providing a constant absorption of energy.After meals, the stomach emptied equal amounts of energydespite large variations in meal composition. Theavailable intestinal absorptive capacity for protein was utilized by 96%, whereas that forcarbohydrate, fat and energy were utilized only by46-62%. Besides reserves in the absorptive capacity, theintestine provided reserves in total length available for absorption. The results indicate a closerelationship between the energy-dependent absorption ofnutrients and the energy-dependent feedback inhibitionof gastric emptying.
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