Intestinal Oxygen Uptake and Glucose Metabolism During Nutrient Absorption in the Pig

Abstract

Intestinal transport of nutrients coincides with their partial catabolism in the gut. The aim of the present study was to measure intestinal oxygen consumption and nutrient metabolism after a meal or during a short fast. Nutrient and oxygen balances across the small intestine were measured in conscious 50 kg (live wt) pigs. Jejunal enterocytes were also isolated from 1-hr postprandial, postabsorptive, or 3-day fasted pigs, in order to evaluate their capacities to metabolize 5 mM glucose and 2 mM glutamine. Whatever the nutritional state, intestinal oxygen consumption was high, since 26 +/- 2% (n = 6) of the oxygen arterial supply was extracted by the small intestine. Furthermore, the consumption of a mixed meal induced a rapid and transient rise in oxygen consumption. In the postabsorptive state, the intestinal uptake of glucose (0.31 +/- 0.08 mmole/min, n = 6) was twice higher than that of glutamine. The role of glucose as a fuel was also evidenced after a 3-day fast. During nutrient absorption, glutamine was highly utilized, and lactate was produced. The capacity of enterocytes isolated from fed pigs to metabolize glucose was dramatically reduced, as was 6-phosphofructo 1-kinase activity. In contrast, intestinal muscle presented a high glycolytic capacity from glucose, suggesting that the main site of intestinal lactate production during nutrient absorption would be the muscular rather than the epithelial layer.

Dietary starch sources affect net portal appearance of amino acids and glucose in growing pigs

“…However, consistent with previous studies (Rerat et al, 1984;Leclere et al, 1993;Vaugelade et al, 1994;Van der Meulen et al, 1997), we found that about 35% to 50% of dietary starch did not enter the portal vein as the glucose moiety in growing pigs (Table 6). The amounts of glucose entering the portal vein were higher in pigs fed the maize, sticky rice and brown rice diets than in pigs fed the RS diet (Table 6), possibly due to reduced catabolism of glucose in the gastrointestinal wall.…”

“…Extensive studies have shown that the digestibility of dietary carbohydrates in swine is largely affected by their source, structure and composition as well as by the activities of digestive enzymes (Cone and Vlot, 1990;Franco et al, 1992;Leclere et al, 1993;Weurding et al, 2001). Much evidence also showed that the rate of glucose absorption was tested from the portal vein of pigs (Rerat, 1985;Vaugelade et al, 1994;van der Meulen et al, 1997).…”

Fuel selection in intestinal cells

“…Moreover, in experiments on isolated enterocyte mitochondria, 0 2 consumption related to glutamine oxidation is significantly enhanced by the presence of malate (Evered & Masola, 1984), suggesting that the entry of glutamine into the tricarboxylic acid cycle and/or the efflux of intermediates from the cycle may be stimulated by glucose metabolism (Fleming & Kight, 1994). Under fasting conditions, a high capacity for glutamine oxidation is maintained in isolated enterocytes (Vaugelade et al 1994), although glutaminase activity is slightly depressed (Newsholme & CarriC, 1994). In contrast, glutamine oxidation is profoundly altered during fasting in isolated colonocytes (Firmansyah et al 1989).…”

“…The gastrointestinal tract is a site of high 0 2 uptake, the latter amounting to 2025% of the whole-body 0 2 consumption, even in the post-absorptive or fasting state (Yen et al 1989;Vaugelade et al 1994). The consumption of a meal in humans as well as in animal models is generally accompanied by a rise in energy expenditure.…”

Non-starch polysaccharides extracted from seaweed can modulate intestinal absorption of glucose and insulin response in the pig

“…: 1.27 mm, o.d. : 2.29 mm, Tygon Norton, Cleveland, OH, USA) in the portal vein (PV) and in the right carotid artery (CA), as described previously [25,32], and with an ultrasonic portal blood-flow probe (12 or 14 mm probe, Transonic Systems Ltd, Ithaca, NY, USA). Carotid artery cannulation, allowing to sample blood from the thoracic aorta, has been reported to be the best technique to obtain systemic arterial blood in the pig [33].…”