Effect of food intake level on arterial glycemia, portal glucose appearance and intestinal oxygen consumption in the pig

In this study the glycemic and insulinic responses to a mixed meal of grade d size, have been investigated in a pig model in relation to portal glucose appearance. Additionnally, nutrients potentially contributing to intestina l energy demand during absorption were identified. Nutrient (glucose, gluta mine, and glutamate) and oxygen balances across the small intestine were th us measured over 3 h in conscious 50-60 kg Large White pigs receiving grade d levels of a casein-starch based diet (200, 400 or 800 g). Arterial blood glucose response was similar, irrespective of the food intake level, remain ing high 3 h after the meal, whereas the pattern of net glucose appearance in the portal Vein clearly differed between the 200 g and 800 g feeding lev el. Intestinal oxygen uptake was highly correlated with nutrient (glucose) absorption, both being maximum within 2 h after the meal. This was accompan ied by a high glutamine and glutamate consumption by the intestine, which c ould account for the additional oxygen consumption during nutrient absorpti on. In conclusion, changes in blood glucose concentration in the peripheral blood do not adequately reflect glucose absorption. The latter is accompan ied by an increase of oxygen consumption in the intestine, supported by glu tamine and glutamate (rather than glucose) metabolism.