Changes in intestinal transit and absorption during endotoxemia are dose dependent

Septic patients are often intolerant of enteral feedings due to a combination of motility disturbances and impaired absorptive function. Our laboratory has previously demonstrated that endotoxemia results in rapid intestinal transit and decreased jejunal absorption of water, electrolytes, and glucose. We hypothesized that the changes in jejunal transit and absorption during endotoxemia may be dependent on the dose of endotoxin.

Under general anesthesia, rats underwent placement of an internal jugular line, a femoral arterial line, and a 20-cm jejunal Thiry-Vella loop. The jejunal segment was perfused with an isotonic solution containing polyethylene glycol. For 90 min, baseline measurements of blood pressure, heart rate, jejunal absorption of water, electrolytes, and glucose, and jejunal transit were made. Following this baseline period I, rats were given 0.9% NaCl (1 ml/kg) or one of three doses of Escherichia coli lipopolysaccharide (0.5, 1.0, or 5.0 mg/kg). Studies were then repeated for an additional 90 min.

Changes in blood pressure and heart rate were similar among the four groups of animals. Endotoxin decreased water and glucose flux, increased potassium flux, and quickened intestinal transit in a dose-dependent fashion.

We conclude that endotoxemia causes dose-dependent changes in jejunal transit and absorption. The effects of increasing doses of endotoxin on jejunal absorptive and motor function do not appear to be mediated by changes in blood pressure or heart rate.