L-glutamine with D-glucose stimulates oxidative metabolism and NaCl absorption in piglet jejunum

Abstract

To explore the relationship between intestinal fluid absorption and oxidative metabolism, we measured the effects of amino acids and glucose on piglet jejunal ion transport and oxygen consumption (QO2) in vitro. Jejunal QO2 was stimulated by L-glutamine and D-glucose but not by the nonmetabolizable organic solutes methyl beta-D-glucoside or L-phenylalanine. QO2 was maximally enhanced by the combination of D-glucose and L-glutamine (5 mM). Even though 5 mM L-glutamine was previously found to be insufficient to stimulate NaCl absorption, 5 mM L-glutamine enhanced jejunal NaCl flux when combined with equimolar mucosal D-glucose. Either D-glucose or methyl beta-D-glucoside caused an increase in short-circuit current (Isc), an increase in Na+ absorption in excess of Isc, and a decrease in Cl- secretion, when L-glutamine was substituted for D-glucose (10 mM) on the serosal side. This relationship suggests that mucosal sugars, if combined with L-glutamine, enhance neutral NaCl absorption as well as electrogenic Na+ flow. (Aminooxy)acetate, an inhibitor of alanine aminotransferase, abolished the stimulation of QO2 and the NaCl-absorptive response to L-glutamine. We conclude that the oxidative metabolism fueled by L-glutamine is linked to a NaCl-absorptive mechanism in the intestine. We propose that the CO2 produced by glutamine metabolism yields carbonic acid, which dissociates to H+ and HCO3-, which may stimulate parallel antiports in the apical membrane.

Fuel selection in intestinal cells

“…Stimulation by glucose of intestinal glutamine metabolism and oxidation, also, has been demonstrated in other conditions (Weber et al 1982;Rhoads et al 1992). Indeed, glucose generates pyruvate which is used in the transamination of glutamate (Fig.…”

Dietary supplementation with cholesterol and docosahexaenoic acid affects concentrations of amino acids in tissues of young pigs

“…In addition, glutamate can be synthesized from BCAA by both cytosolic and mitochondrial BCAA transaminase in the brain. Glutamate–oxaloacetate transaminase activity is widely spread in animal tissues to synthesize aspartate from glutamate (Rhoads et al 1992). Thus, we surmise that dietary supplementation with cholesterol or DHA may reduce the uptake of either acidic AA and/or their precursors (glutamine and BCAA), as well as the activity of glutamate decarboxylase for GABA synthesis by the brain.…”

Development of Intestinal Transport Function in Mammals

“…Ϫ secretion have not yet been fully investigated, even though acid secretion in the stomach is not fixed in adult form at birth (1,438). Active Cl Ϫ secretion was observed in the small intestine of suckling mice and pigs (252,320) and in the distal colon of suckling rabbits (67, 308, 310). The product of cystic fibrosis transmembrane conductance regulator gene encoding a cAMP-regulated Cl Ϫ channel has already been demonstrated in the human fetal small and large intestine, and its abundance was relatively stable during prenatal development (127, 402,408).…”

“…ATP, which is produced by oxidative phosphorylation and partially also by glycolysis, is utilized by various ion pumps (ATPases) to cover the expenditure required for transport work. Even if the detailed mechanisms of coupling between ATP production and ATP consumption (hydrolysis) are not fully understood, both processes are coupled in the intestinal epithelium similarly as in other epithelia (8,225,320).…”