Prolonged endotoxemia enhances the renal injuries induced by gentamicin in rats

The aim of this study was to evaluate the role of chronic endotoxemia in the nephrotoxicity of gentamicin (GM). Saline or Escherichia coli lipopolysaccharide (LPS) was administered to conscious rats by continuous intravenous perfusion (1 mg/kg per day for 7 days) from a subcutaneously implanted osmotic pump. Twenty-four hours after surgery (day zero), treatment with saline or GM (15 mg/kg; intraperitoneally, twice a day) was started for 5 days. Levels of LPS in plasma measured by Limulus amoebocyte lysate activity decreased significantly from days 1 through 8. At days 5 and 8, the cortical concentrations of GM were higher in the LPS-perfused and GM-treated group (LPS plus GM) than they were in the saline-perfused and GM-treated group (saline plus GM) (P less than 0.05). Blood urea nitrogen and serum creatinine remained at normal levels throughout the experiment. A significant increase of cortical tubular cell regeneration was observed in the LPS plus GM animals as compared with regeneration observed in the other groups (saline plus saline, LPS plus saline, and saline plus GM), as measured by [3H]thymidine incorporation into DNA. Moreover, histopathological nephrotoxicity scores showed a synergistic toxic effect between LPS and GM. These results demonstrate that chronic perfusion of low doses of LPS potentiates the nephrotoxicity of GM.