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Endotoxin and renal glutamine metabolism
T R Austgen1, M K Chen, W Moore
1Department of Surgery, University of Florida College of Medicine, Gainesville 32610.
Archives of Surgery (Chicago, Ill. : 1960)
|January 1, 1991
Summary
Endotoxin exposure shifts kidney function from glutamine uptake to release, impacting acid-base balance. This study reveals how endotoxin alters renal glutamine metabolism during critical illness.
Area of Science:
- Renal physiology
- Metabolic biochemistry
Background:
- Critical illness is characterized by altered glutamine metabolism.
- The kidney's role in glutamine handling and acid-base balance is crucial.
Purpose of the Study:
- To investigate the effect of endotoxin on renal glutamine metabolism and ammoniagenesis in vivo.
- To understand altered glutamine flow during critical illness.
Main Methods:
- Rats were administered a single dose of Escherichia coli lipopolysaccharide (endotoxin).
- Renal blood flow, arterial glutamine concentration, and urinary ammonia excretion were measured 15 hours post-administration.
- Renal glutamine synthetase and glutaminase activity were assessed.
Main Results:
- The kidney transitioned from glutamine uptake in controls to net release in endotoxin-treated rats.
- Renal glutamine synthetase activity increased by nearly 50% post-endotoxin, while glutaminase remained unchanged.
- Urinary ammonia excretion decreased by 35% despite reduced arterial bicarbonate levels.
Conclusions:
- Endotoxin significantly alters net glutamine flux across the kidney.
- Enzymatic regulation plays a role in endotoxin-induced changes in renal glutamine metabolism.
- These metabolic alterations may impair the kidney's capacity to maintain acid-base homeostasis during critical illness.