OBJECTIVETo investigate the effects of lipopolysaccharide (LPS) and heat co-exposure on serum urea and creatinine (Cr) concentrations in rats.

METHODSMale Wistar rats were randomized into normothermic saline injection control group (group C), heat exposure saline injection group (group H), normothermic LPS injection group (group L), and heat exposure LPS injection group (group HL). The rats in groups H and HL were exposed to heat in a chamber at an dry bulb temperature (Tdb) of 35.0-/+0.5 degrees Celsius, and those in groups C and L were kept in a chamber at Tdb of 26-/+0.5 degrees Celsius. LPS (8 mg/kg) was injected via the tail vein in the rats in groups L and HL to induce endotoxemia, while those in groups C and H were given normal saline injection (8 ml/kg) via the tail vein. The serum levels of urea and Cr were determined at the time points of 0, 40, 80, and 120 min after the injections.

RESULTSNo significant difference was found in serum Cr level at any level of the main effects of time, drug, or Tdb (P>0.05), but serum urea level varied significantly between the different time points, different levels of Tdb, and the drug injections (P<0.01). Significant interactions were identified between the time after injection, injected agents, and Tdb (P<0.01). Except for those in the group C, all rats showed elevated serum urea levels 40 min after the injection, particularly those in group HL. The serum urea levels were positively correlated to the level of tumor necrosis factor-alpha (P<0.01).

CONCLUSIONCo-exposure to LPS and heat in rats may elicit and worsen systemic inflammatory response syndrome and kidney injury.