The maximal activity of phosphate-dependent glutaminase and glutamine metabolism in late-pregnant and peak-lactating rats

Abstract

The maximal activity of phosphate-dependent glutaminase was increased in the small intestine, decreased in the liver and unchanged in the kidney of late-pregnant rats. This was accompanied by increases in the size of both the small intestine and the liver. The maximal activity of phosphate-dependent glutaminase was increased in both the small intestine and liver but unchanged in the kidney of peak-lactating rats. Enterocytes isolated from late-pregnant or peak-lactating rats exhibited an enhanced rate of utilization of glutamine and production of glutamate, alanine and ammonia. Arteriovenous-difference measurements across the gut showed an increase in the net glutamine removed from the circulation in late-pregnant and peak-lactating rats, which was accompanied by enhanced rates of release of glutamate, alanine and ammonia. Arteriovenous-difference measurements for glutamine showed that both renal uptake and skeletal-muscle release of glutamine were not markedly changed during late pregnancy or peak lactation; but pregnant rats showed a hepatic release of the amino acid. It is concluded that, during late pregnancy and peak lactation, the adaptive changes in glutamine metabolism by the small intestine, kidneys and skeletal muscle of hindlimb are similar; however, the liver appears to release glutamine during late pregnancy, but to utilize glutamine during peak lactation.

Endotoxemia affects citrulline, arginine and glutamine bioavailability

“…The intestine possesses a glutaminase enzyme with a higher activity than in other tissues [39]. However, during sepsis gut, glutaminase activity decreases, whereas it increases in lymphocytes [40–45]. Changes in glutamine utilisation by the intestine may permit its uptake and efficient use by immune cells.…”

Aspects of organ protein, amino acid and glucose metabolism in a porcine model of hypermetabolic sepsis

“…During endotoxaemia, the net output of alanine and glutamine from the muscle exceeded the net consumption by the splanchnic organs ( Figure 3B compared with Figure 3A). The ' excess ' glutamine is probably used by the kidney and lymphoid tissue [52], while the excess alanine may be involved as a substrate for brain and nerve tissue [53]. Net efflux of BCAA from the hindquarters was observed during endotoxaemia, indicating that the rate of release of BCAA derived from accelerated protein degradation exceeded the increase in BCAA consumption by the hindquarters.…”

Aspects of organ protein, amino acid and glucose metabolism in a porcine model of hypermetabolic sepsis

“…This indicates that, during sepsis, intracellular glutamate serves increased de novo synthesis of alanine and glutamine. The ' excess ' glutamine is probably used by the kidney and lymphoid tissue [52], while the excess alanine may be involved as a substrate for brain and nerve tissue [53]. The ' excess ' glutamine is probably used by the kidney and lymphoid tissue [52], while the excess alanine may be involved as a substrate for brain and nerve tissue [53].…”