The Effects of Sepsis and Endotoxemia on Gut Glutamine Metabolism

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Abstract
The effects of sepsis on gut glutamine (GLN) metabolism were studied to gain further insight into the regulation of the altered glutamine metabolism that characterizes critical illnesses. Studies were done in laboratory rats and in hospitalized patients. The human studies were done in seven healthy surgical patients (controls) and six septic patients who underwent laparotomy. Radial artery and portal vein samples were obtained during operation and were analyzed for GLN and oxygen content. Despite no reduction in arterial glutamine concentration in the septic patients, gut glutamine extraction was diminished by 75% (12.0% +/- 1.6% in controls vs. 2.8% +/- 0.8% in septic patients, p less than 0.01). Similarly gut oxygen extraction was diminished by nearly 50% in the septic patients (p less than 0.05). To further investigate these abnormalities, endotoxin (10 mg/kg intraperitoneally) or saline (controls) was administered to adult rats 12 hours before cannulation of the carotid artery and portal vein. The arterial GLN concentration was increased by 13% in the endotoxin-treated animals (p less than 0.05) but gut glutamine uptake was diminished by 46% (526 +/- 82 nmol/100 g BW/minute in controls vs. 282 +/- 45 in endotoxin, p less than 0.01). Simultaneously gut glutaminase activity was diminished by 30% (p less than 0.01) and intestinal glutamate release fell by two thirds. Blood cultures were negative in control animals (0 of 20), but were positive in 25% of endotoxemic animals (6 of 24) for gram-negative rods (p = 0.019). Sepsis and endotoxemia impair gut glutamine metabolism. This impairment may be etiologic in the breakdown of the gut mucosal barrier and in the development of bacterial translocation.