Corticosteroids increase glutamine utilization in human splanchnic bed

TitleCorticosteroids increase glutamine utilization in human splanchnic bed
Publication TypeJournal Article
Year of Publication2008
AuthorsThibault, R., Welch S., Mauras N., Sager B., Altomare A., Haymond M., & Darmaun D.
JournalAmerican journal of physiology. Gastrointestinal and liver physiology
Volume294
Issue2
PaginationG548-53
Date Published2008 Feb
ISSN0193-1857
KeywordsAdrenal Cortex Hormones; Adult; Female; Glutamine; Humans; Kinetics; Leucine; Male; Oxidation-Reduction; Prednisone; Splanchnic Circulation
Abstract

Glutamine is the most abundant amino acid in the body and is extensively taken up in gut and liver in healthy humans. To determine whether glucocorticosteroids alter splanchnic glutamine metabolism, the effect of prednisone was assessed in healthy volunteers using isotope tracer methods. Two groups of healthy adults received 5-h intravenous infusions of l-[1-(14)C]leucine and l-[(2)H(5)]glutamine, along with q. 20 min oral sips of tracer doses of l-[1-(13)C]glutamine in the fasting state, either 1) at baseline (control group; n = 6) or 2) after a 6-day course of 0.8 mg.kg(-1).day(-1) prednisone (prednisone group; n = 8). Leucine and glutamine appearance rates (Ra) were determined from plasma [1-(14)C]ketoisocaproate and [(2)H(5)]glutamine, respectively, and leucine and glutamine oxidation from breath (14)CO(2) and (13)CO(2), respectively. Splanchnic glutamine extraction was estimated by the fraction of orally administered [(13)C]glutamine that failed to appear into systemic blood. Prednisone treatment 1) did not affect leucine Ra or leucine oxidation; 2) increased plasma glutamine Ra, mostly owing to enhanced glutamine de novo synthesis (medians +/- interquartiles, 412 +/- 61 vs. 280 +/- 190 mumol.kg(-1).h(-1), P = 0.003); and 3) increased the fraction of orally administered glutamine undergoing extraction in the splanchnic territory (means +/- SE 64 +/- 6 vs. 42 +/- 12%, P < 0.05), without any change in the fraction of glutamine oxidized (means +/- SE, 75 +/- 4 vs. 77 +/- 4%, not significant). We conclude that high-dose glucocorticosteroids increase in splanchnic bed the glutamine requirements. The role of such changes in patients receiving chronic corticoid treatment for inflammatory diseases or suffering from severe illness remains to be determined.

Alternate JournalAm. J. Physiol. Gastrointest. Liver Physiol
Refereed DesignationRefereed