Metabolic fate of glutamine in lymphocytes, macrophages and neutrophils

Eric Newsholme's laboratory was the first to show glutamine utilization by lymphocytes and macrophages. Recently, we have found that neutrophils also utilize glutamine. This amino acid has been shown to play a role in lymphocyte proliferation, cytokine production by lymphocytes and macrophages and phagocytosis and superoxide production by macrophages and neutrophils. Knowledge of the metabolic fate of glutamine in these cells is important for the understanding of the role and function of this amino acid in the maintenance of the proliferative, phagocytic and secretory capacities of these cells. Glutamine and glucose are poorly oxidized by these cells and might produce important precursors for DNA, RNA, protein and lipid synthesis. The high rate of glutamine utilization and its importance in such cells have raised the question as to the source of this glutamine, which, according to current evidence, appears to be muscle

Effect of trolox C on cardiac contratucture induced by hydrogen peroxide

Hydrogen peroxide (H2O2) perfused into the aorta of the isolated rat heart induces a positive inotropic effect, with cardiac arrhythmia such as extrasystolic potentiation or cardiac contractures, depending on the dose. The last effect is similar to the "stone heart" observed in reperfusion injury and may be ascribed to lipoperoxidation (LPO) of the membrane lipids, to protein damage, to reduction of the ATP level, to enzymatic alterations and to cardioactive compounds liberated by LPO. These effects may result in calcium overload of the cardiac fibers and contracture ("stone heart"). Hearts from male Wistar rats (300-350g) were perfused at 31°C with Tyrode, 0.2 mM trolox C, 256 mM H2O2 or trolox C + H2O2. Cardiac contractures (baseline elevation of the myograms obtained) were observed when hearts were perfused with H2O2 (Tyrode: 5.9 + 3.2; H2O2: 60.5 + 13.9 percent of the initial value); perfusion with H2O2 increased the LPO of rat heart homogenates measured by chemiluminescence (Tyrode: 3,199 + 259; H2O2: 5,304 + 133 cps mg protein(-1) 60 min(-1), oxygen uptake (Tyrode: 0.44 + 0.1; H2O2: 3.2 + 0.8 nmol min(-1) mg protein(-1) and malonaldehyde (TBARS) foramtion (Tyrode: 0.12 + 0; H2O2: 0.37 + 0.1 nmol/ml). Previous perfusion with 0.2 mM trolox C reduced the LPO (Chemiluminescence: 4,098 + 531), oxygen uptake (0.51 + 0) and TBARS (0.13 + 0) bud did not prevent the H2O2-induced contractures (33.3 + 16 percent). ATP (Tyrode: 2.84 + 0; H2O2: 0.57 + 0) and glycogen levels (Tyrode: 0.46 + 0; H2O22: 0.26 + 0) were reduced by H2O2. Trolox did not prevent these effects (ATP: 0.84 + 0 and glycogen: 0.27 + 0). Trolox C is known to be more effective than alpha-tocopherol or gamma-tocopherol in reducing LPO though it lacks the phytol portion of vitamin E to be fixed to the cell membranes. Trolox C, unlike vitamin A, did not prevent the glycogen reduction induced by H2O2. Trolox C induced a positive chronotropic effect that resulted in higher energy consumption. The reduction of energy level seemed to be more important than LPO in the mechanism of H2O2-induced contracture.

Effect of aging on the glutaminase activity of neoplastic and immune tissues

1. The effect of age and Walker 256 tumor on maximal phosphate-dependent glutaminase activity of rat immune tissue was determined. Glutaminase is a key enzyme in the metabolism of glutamine, an important fuel for normal and neoplastic cells. 2. Maximal activity of phosphate-dependent glutaminase was measured in immune tissues and tumors of Walker 256 tumor-bearing young (28 days old), mature (3 months old) and aged (15 months old) Wistar rats. The following tissues were examined: thymus, spleen, mesenteric lymph nodes and tumor. 3. Tumor implantation for 14 days reduced glutaminase activity in the thymus and mesenteric lymph nodes. Tumor glutaminase activity was lowest in aged rats and highest in the mature group. 4. Comparison of glutaminase activity in immune and tumor tissues suggested the flux of glutamine between these tissues in the 3 groups. Glutaminase activity was 2.8-fold higher in immune tissues in aged rats (2.58 +/- 0.35 vs 0.93 +/- 0.16 mumol min-1 g tissue wet weight-1, mean +/- SEM, 5 rats), and 1.9- (4.14 +/- 0.47 vs 8.36 +/- 1.29 mumol min-1 g tissue wet weight-1, mean +/- SEM, 5 rats) and 2.5-fold increased (2.41 +/- 0.20 vs 5.92 +/- 0.22 mumol min-1 g tissue wet weight-1, mean +/- SEM, 5 rats) in tumor tissue in the mature and young groups, respectively. These results suggest the deviation of glutamine flux from defense cells to the neoplastic tissue in tumor-bearing young and mature rats and may partially explain the slow cancer growth in elderly patients

Effects of aspirin-like drugs on Walker 256 tumor growth and cachexia in rats

Several studies have shown the relationship between prostaglandins (PGs) and cell proliferation. Some PGs may trigger cell dibision or are involved in this process. This a=study analyzes the effect of PG biosyntheseis inhibitors on tumor growth in vivo and cachexia in Walker 256 tumor-bearing rats. Indomethacin markedly inhibited tumor growth (95.5% while ibuprofen and aspirin reduced tumor growth by 73.9% and 59.4%, respectively. In addition, all drug-treated rats partially recovered body weight and food intake as compared to the saline-treated group. These findings suggest that PG synthesis inhibitors improve cancer cachexia