Glutamine and glucose metabolism in enterocytes of the neonatal pig

Abstract

Glutamine and glucose metabolism was studied in 0- to 21-day-old pig enterocytes. Cells were incubated at 37 degrees C for 30 min in Krebs-Henseleit bicarbonate buffer (pH 7.4) in the presence of 2 mM [U-14C]glutamine with or without 5 mM glucose, or 5 mM [U-14C]glucose with or without 2 mM glutamine. Glutamine was metabolized to ammonia, glutamate, alanine, aspartate, CO2, citrulline, ornithine, and proline, whereas glucose was converted to lactate, pyruvate, and CO2 in pig enterocytes. CO2 production from glutamine accounted for 32-36% and 3-4% of utilized glutamine carbons in 0- to 7-day-old and 14- to 21-day-old pigs, respectively. The rates of O2 consumption and metabolism of glutamine and glucose decreased in enterocytes from 2- to 14-day-old pigs compared with 0-day-old pigs. By day 14 after birth, the oxidation of glutamine and glucose as well as citrulline production had decreased by 90-95%. Arginine synthesis from glutamine occurred in cells from 0- to 7-day-old pigs but not 14- to 21-day-old ones. Glucose (5 mM) had no effect on glutamine utilization and oxidation or the production of glutamate and arginine but stimulated the formation of alanine, citrulline, and proline at the expense of aspartate. In contrast, glutamine (2 mM) inhibited glycolysis and glucose oxidation in cells from 0- to 7-day-old pigs and had no effects in 14- to 21-day-old pigs. As a result, glutamine contributed approximately 2-fold greater amounts of ATP to 0- to 7-day-old pig enterocytes than glucose.(ABSTRACT TRUNCATED AT 250 WORDS)

Arginine metabolism: nitric oxide and beyond

“…At birth, the small intestine is the major site of net arginine synthesis [75,77], but gradually becomes the major site of net citrulline production as intestinal arginase expression increases [77][78][79][80]. This transition is compensated for by the gradually increasing capacity of the kidney to synthesize arginine from citrulline [73,79,81].…”

Desempenho e morfometria intestinal de juvenis de tilápia-do-nilo alimentados com dietas suplementadas com L-glutamina e L-glutamato

“…O glutamato e a glutamina possuem via metabólica comum no enterócito, pois a glutamina é metabolizada em glutamato mais amônia pela glutaminase e o glutamato também pode se transformar em glutamina pela ação da glutamina sintetase (Maiorka et al, 2000). Dessa forma, o glutamato pode substituir a glutamina em diversos de seus papéis metabólicos, como geração de energia e síntese de aminoácidos (Wu et al, 1995).…”

Impact of bioactive substances on the gastrointestinal tract and performance of weaned piglets: a review

“…From the literature, five AA, namely glutamine, tryptophan, arginine, cysteine and threonine, showed consistent bioactivity with respect to physiology, immunology, endocrinology and metabolism. Glutamine (Wu et al, 1995) and glutamate (Reeds et al, 2000) are important fuels for intestinal epithelial cells. Notwithstanding the stresses of weaning, these AA were able to maintain the high turnover of the gut mucosa, as indicated by longer villi in pigs supplemented with glutamine (Ayonrinde et al, 1995;Liu et al, 2002;Lee et al, 2003;Domeneghini et al, 2004 and or glutamate (Liu et al, 2002).…”