Failure of intestinal amino acid absorptive mechanisms in sepsis

Sepsis has been shown to impair the barrier function and metabolism of the intestine. This study was done to investigate the effect of sepsis on intestinal absorption of proline, leucine, glutamic acid, and aminoisobutyric acid.

Rats (six per group) were studied 24 hours after cecal ligation and puncture (CLP) or six hours after intraperitoneal injection of lipopolysaccharide (LPS). Controls underwent sham laparotomy or saline solution injection. Four 7-cm everted proximal jejunal sacs were prepared from each rat and filled with 800 microL Krebs' bicarbonate buffer containing 100 mumol/L of amino acid. Paired sacs (septic and control) were incubated at 37 degrees C in flasks containing the same solution trace labeled with 3H containing the same solution trace labeled with 3H amino acid. Sac contents were aspirated 60 minutes later and amino acid uptake was determined by scintillation counting.

Twenty-four hours after CLP and six hours after LPS administration there was significant impairment in the intestinal absorption of all amino acids studied. Absorption of glutamic acid was the least affected, followed by leucine, aminoisobutyric acid, and proline.

Sepsis impairs the intestinal absorption of amino acids. The magnitude of this defect in absorption differed with the amino acid studied, suggesting that not all transport systems were affected equally. This differential response of transport systems to sepsis appears to be the inverse of what is observed after a period of starvation.