glutaminase and Sepsis

Berberine was reported to protect against the intestinal injury and improve the survival rate in sepsis, and glutamine deficiency was considered to be correlated with mortality in sepsis. We found that berberine pretreatment ameliorated lipopolysaccharide-induced direct intestinal injury and mucosal hypoplasia and attenuated impairments of intestinal glutamine transport and glutaminase activity, B(0)AT1 mRNA and protein expressions, and glutaminase protein expression. These findings showed the first time that berberine pretreatment could improve intestinal recovery and attenuate the impairment of glutamine transport and glutaminase activity in rat sepsis. This might be one of the mechanisms for the beneficial effect of berberine on sepsis.

Topics: Amino Acid Transport Systems, Neutral; Animals; Berberine; Biological Transport; Glutaminase; Glutamine; Intestinal Mucosa; Intestines; Lipopolysaccharides; Phytotherapy; Plant Extracts; Rats; Rats, Sprague-Dawley; RNA, Messenger; Sepsis

Previous reports have emphasized increased intestinal glutamine consumption during sepsis. This may be of clinical significance as glutamine is a (and perhaps the) physiologic fuel for the intestine. A problem remains, however, as glutaminase, the major enzyme for the degradation of glutamine, is decreased rather than increased in sepsis. This implies an alteration in the metabolic fate of glutamine in sepsis, which may be of clinical significance.. We determined the effect of sepsis on glutamine metabolism in mucosa of small intestine. Sepsis was induced in rats by cecal ligation and puncture. Control rats were sham-operated. After 16 hours, glutamine consumption was measured in isolated enterocytes, and glutaminase, glutamine synthetase, and glutamine transaminase activities and DNA synthesis were determined in mucosa.. Glutamine consumption was increased during sepsis in enterocytes from the tips of the villi and was unchanged in enterocytes from the midportions of the villi and the crypts. As previously shown, mucosal glutaminase activity was reduced. However, glutamine synthetase and glutamine transaminase activities were stimulated in septic rats, suggesting an increase in metabolism of glutamine via alternate pathways. DNA synthesis was increased during sepsis, especially in crypt cells.. Increased or unchanged glutamine consumption in enterocytes from septic rats, despite reduced glutaminase activity, appears to reflect increased activity of other enzyme systems and/or increased utilization of the amino acid for DNA and protein synthesis. Since other aspects of glutamine metabolism may also be deranged in sepsis, a continual enteral supply of glutamine to the intestinal lumen during sepsis may be clinically useful.

Topics: Animals; Carbon Dioxide; Cell Separation; DNA; Epithelium; Glutamate-Ammonia Ligase; Glutaminase; Glutamine; In Vitro Techniques; Intestinal Mucosa; Jejunum; Male; Rats; Rats, Sprague-Dawley; Sepsis; Thymidine; Transaminases

We observed the influence of recombinant growth hormone (rGH) on protein metabolism during sepsis and found its mechanisms. Cecal ligation and puncture were choosen to duplicate the severe infection model. Animals of therapy group received rGH 1 U/kg/d after CLP operation, while sepsis group received normal saline. rGH accelerated regaining of the positive nitrogen equilibrium, improved plasma albumin level. rGH accelerated the recovery of intestinal mucosa glutaminase activity, preserved the normal structure of intestinal mucosa, reduced the portal venous endotoxin level and venous TNF level. rGH improved the albumin synthesis of isolated hepatocytes, and inhibited the expression of albumin mRNA level during severe infection. We conelude that rGH preserves the normal structure and function of intestinal mucosa during sepsis, and reduces gut origin hypermetabolism reactions. Moreover, rGH improves the synthesis of protein.

Topics: Albumins; Animals; Glutaminase; Growth Hormone; Intestinal Mucosa; Liver; Male; Peritoneal Diseases; Rats; Rats, Sprague-Dawley; RNA, Messenger; Sepsis; Serum Albumin

The effects of cytokines on intestinal glutamine metabolism were studied to gain further insight into the regulation of altered glutamine metabolism that occurs during severe infection. One hundred thirteen adult rats were given a single dose of interleukin-1 (IL-1, 50 micrograms/kg), tumor necrosis factor (TNF, 50 micrograms/kg or 150 micrograms/kg), or saline (controls), and flux studies were performed 4 or 12 hours later. Intestinal blood flow was not different between control and cytokine-treated animals at either time point. At the 4-hour time point, arterial glutamine fell by 16% to 21% in the cytokine-treated animals (p less than 0.05); at the 12-hour time point, the arterial glutamine concentration had returned to normal. Intestinal glutamine extraction decreased in the animals treated with IL-1 at both time points (4 hours: 13% +/- 1.3% in IL-1 versus 20% +/- 1.6% in controls, p less than 0.05; and 12 hours: 9% +/- 2% in IL-1 versus 17% +/- 2% in controls, p less than 0.05). Consequently, net intestinal glutamine uptake fell in the animals treated with IL-1 at both time points (p less than 0.05). Similarly, the activity of mucosal glutaminase, the principal enzyme of glutamine hydrolysis in the gut, fell by 50% in the 4-hour study (6.1 +/- 0.6 mumol/h/mg protein in IL-1 versus 9.6 +/- 0.8 mumol/h/mg protein in controls, p less than 0.01) and by 40% in the 12-hour study (5.4 +/- 0.5 mumol/h/mg protein in IL-1 versus 8.8 +/- 0.4 mumol/h/mg protein in controls, p less than 0.05). Concomitant with the aforementioned decrease in gut glutamine metabolism was a 25% incidence of positive blood cultures for gram-negative organisms in IL-1 treated rats studied at the 12-hour time point (p = 0.05 versus controls). In the doses administered and at the time points studied, TNF had no effects on the parameters of gut glutamine metabolism examined. The results indicate that IL-1 is a potential mediator of the alterations in gut glutamine metabolism observed in sepsis and endotoxemia.

Topics: Animals; Bacterial Infections; Glutaminase; Glutamine; Interleukin-1; Intestinal Mucosa; Male; Rats; Rats, Inbred Strains; Sepsis; Time Factors; Tumor Necrosis Factor-alpha

The effects of severe infection on luminal transport of amino acids and glucose by the small intestine were investigated. Studies were done in endotoxin-treated rats and in septic patients who underwent resection of otherwise normal small bowel. In rats the kinetics of the brush border glutamine transporter and the glutaminase enzyme were examined. In patients the effects of severe infection on the transport of glutamine, alanine, leucine, and glucose were studied. Transport was measured using small intestinal brush border membrane vesicles that were prepared by Mg++ aggregation/differential centrifugation. Uptake of radiolabeled substrate was measured using a rapid mixing/filtration technique. Vesicles demonstrated 15-fold enrichments of enzyme markers, classic overshoots, transport into an osmotically active space, and similar 2-hour equilibrium values. The sodium-dependent pathway accounted for nearly 90% of total carrier-mediated transport. Kinetic studies on rat jejunal glutaminase indicated a decrease in activity as early as 2 hours after endotoxin secondary to a decrease in enzyme affinity for glutamine (Km = 2.23 +/- 0.20 mmol/L [millimolar] in controls versus 4.55 +/- 0.67 in endotoxin, p less than 0.03), rather than a change in Vmax. By 12 hours the decrease in glutaminase activity was due to a decrease in Vmax (222 +/- 36 nmol/mg protein/min in controls versus 96 +/- 16 in endotoxin, p less than 0.03) rather than a significant change in Km. Transport data indicated a decrease in sodium-dependent jejunal glutamine uptake 12 hours after endotoxin secondary to a 35% reduction in maximal transport velocity (Vmax = 325 +/- 12 pmol/mg protein/10 sec in controls versus 214 +/- 8 in endotoxin, p less than 0.0001) with no change in Km (carrier affinity). Sodium-dependent glutamine transport was also decreased in septic patients, both in the jejunum (Vmax for control jejunum = 786 +/- 96 pmol/mg protein/10 sec versus 417 +/- 43 for septic jejunum, p less than 0.01) and in the ileum (Vmax of control ileum = 1126 +/- 66 pmol/mg protein/10 sec versus 415 +/- 24 in septic ileum, p less than 0.001) The rate of jejunal transport of alanine, leucine, and glucose was also decreased in septic patients by 30% to 50% (p less than 0.01). These data suggest that there is a generalized down-regulation of sodium-dependent carrier-mediated substrate transport across the brush border during severe infection, which probably occurs secondary to a decrease in transporter sy

Topics: Adult; Animals; Biological Transport; Endotoxins; Escherichia coli Infections; Glutaminase; Glutamine; Humans; Intestine, Small; Kinetics; Male; Microvilli; Rats; Rats, Inbred Strains; Sepsis

The activity of phosphate-dependent glutaminase and glutamine metabolism by tissues known markedly to utilize or synthesize glutamine (or both) were studied in rats made septic by cecal ligation and puncture technique and compared with the same measures in rats that underwent sham operation (laparotomy). Blood glucose level was not markedly different in septic rats, but lactate, pyruvate, alanine, and glutamine levels were markedly increased. Conversely, blood ketone body concentrations were significantly decreased in septic rats. Both plasma insulin and glucagon levels were markedly elevated in response to sepsis. The maximal activity of phosphate-dependent glutaminase was decreased in the small intestine, increased in the kidney and mesenteric lymph nodes, and unchanged in the liver of septic rats. Arteriovenous concentration difference measurements across the gut showed a decrease in the net glutamine removed from the circulation in septic rats. Arteriovenous concentration difference measurements for glutamine showed that both renal uptake and skeletal muscle release of the amino acid were increased in response to sepsis, whereas measurements across the hepatic bed showed a net uptake of glutamine in septic rats. Enterocytes isolated from septic rats exhibited a decreased rate of utilization of glutamine and production of glutamate, alanine, and ammonia, whereas lymphocytes isolated from septic rats showed an enhanced rate of utilization of glutamine and production of glutamate, aspartate, and ammonia. It is concluded that, during sepsis, glutamine uptake and metabolism are enhanced in renal and lymphoid tissue but decreased in that of the small intestine, with increased rates of release by skeletal muscle; however, the liver appears to utilize glutamine in septic rats.

Topics: Alanine; Animals; Arteries; Glutaminase; Glutamine; Intestinal Mucosa; Kidney; Lactates; Lactic Acid; Liver; Lymph Nodes; Lymphocytes; Male; Phosphates; Pyruvates; Pyruvic Acid; Rats; Rats, Inbred Strains; Sepsis; Veins