Response of glutamine metabolism to exogenous glutamine in humans

Abstract

To determine whether exogenous glutamine affects whole body glutamine metabolism, preliminary experiments were performed to verify that L-[1-13C]-, L-[U-14C]-, and L-[3,4-3H]glutamine given simultaneously by vein provided similar estimates of glutamine appearance rates [Ra; 355 +/- 24, 373 +/- 19, and 393 +/- 24 (SE) mumol.kg-1.h-1, respectively, P = NS] in six healthy men; glutamine oxidation accounted for 32 +/- 3 and 51 +/- 5% (P < 0.01) of glutamine Ra when it was measured using L-[U-14C]- and L-[1-13C]glutamine, respectively. Five subjects received two 5-h intravenous infusions of L-[3,4-3H]glutamine and a simultaneous nasogastric infusion of L-[1-13C]glutamine on 2 separate days in the postabsorptive state, along with saline on 1 day and natural L-glutamine (856 +/- 45 mumol.kg-1.h-1) on another day in a randomized order. Splanchnic glutamine extraction (determined from [13C]glutamine appearance into systemic blood) reached 74 +/- 4 and 53 +/- 5% during the enteral infusion of tracer alone and in combination with a large load of glutamine, respectively. Glutamine infusion was associated with increased plasma glutamine concentration (from 630 +/- 50 to 1,297 +/- 75 microM), Ra (from 258 +/- 20 to 589 +/- 45 mumol.kg-1.h-1), and oxidation (from 179 +/- 20 to 477 +/- 47 mumol.kg-1.h-1, all P < 0.01), no change in glutamine release from proteolysis, and a decline in glutamine de novo synthesis (from 156 +/- 15 to 93 +/- 13 mumol.kg-1.h-1).(ABSTRACT TRUNCATED AT 250 WORDS)

Corticosteroids increase glutamine utilization in human splanchnic bed

“…The model used to quantify splanchnic glutamine uptake in the present studies is similar to that used in healthy subjects by us (4,18) and others (17) in previous studies. The simultaneous infusion of [ 13 C]glutamine via the oral route was designed to trace the appearance of enterally administered glutamine into the systemic circulation.…”

“…In several animal models of sepsis, increased rates of glutamine splanchnic extraction have been reported (27,40,41), but little is known in humans. In the present paper, the fate of splanchnic glutamine was examined by using the concomitant infusion of (18), the choice of tracer is unlikely to account for the observed changes in glutamine kinetics associated with prednisone. Accordingly, the 42% fractional extraction in the first pass in healthy controls under baseline conditions in the present report is consistent with the 50 -74% extraction of enterally administered glutamine documented in earlier studies (4,17,18,33).…”

“…In the present paper, the fate of splanchnic glutamine was examined by using the concomitant infusion of (18), the choice of tracer is unlikely to account for the observed changes in glutamine kinetics associated with prednisone. Accordingly, the 42% fractional extraction in the first pass in healthy controls under baseline conditions in the present report is consistent with the 50 -74% extraction of enterally administered glutamine documented in earlier studies (4,17,18,33). Consistent with previous reports, oxidation was the main fate of glutamine, as oxidation accounted for 75% of glutamine flux, compared with 69 and 83% in earlier studies (17,18).…”

“…By using this technique, ϳ50 to 75% of enterally administered glutamine undergoes first-pass extraction within the splanchnic bed, presumably by the gut and liver, in healthy humans (4,17,18,34). Additionally, the major fate of splanchnic glutamine after enteral administration was oxidation, since 83% of the total tracer extracted was oxidized and only 10% was used for gluconeogenesis (17).…”

Nutritional support with glutamine according to recommendations of the European Society for Clinical Nutrition and Metabolism (ESPEN)

“…Jej stę-żenie w osoczu waha się w granicach 0,5-0,8 mM (średnio 0,65 mM), a w tkance mięśniowej, która jest głównym producentem tego aminokwasu, wynosi ok. 20 mM [2,3]. Źródłem glutaminy w organizmie czło-wieka w 60% jest jej endogenna synteza, pozostałe 40% dostarczane jest wraz z pokarmem i z wewnątrz-komórkowej degradacji białek [4]. Wykazano, że wykorzystywana jest ona przez wiele narządów i tkanek, gdzie pełni określone funkcje.…”