Prophylactic corticosteroid suppresses endotoxemia in heat-stressed primates.

Abstract

We previously found that lipopolysaccharides (LPS) leak from the gut lumen into the hepatic portal vein during heat stroke. Furthermore, we found that prophylactic corticosteroid administration could prevent a rise in plasma LPS concentration in superior mesenteric artery occlusion shock. In this study, we found that treatment prior to heat-stress with corticosteroids could prevent any rise in plasma LPS concentration in heat-stressed primates. Two groups of primates, one of which received a prophylactic dose of methylprednisolone sodium succinate (MPSS) (n = 4) were subjected to heat-stress (41 +/- 0.3 degrees C). Their arterial blood pressure, heart rate and rectal temperature (Tr) were continuously recorded. In the untreated control group (n = 8), the plasma LPS concentration tended to increase slowly at a Tr of 41.5 degrees C from an initial 0.06 +/- 0.013 ng.ml-1. Above a Tr of 43 degrees C, the plasma LPS level rose rapidly until at a Tr of 44.4 +/- 0.1 degrees C, the mean LPS level was 0.315 +/- 0.03 ng.ml-1 (p less than 0.001). Prophylactic treatment with MPSS suppressed the increase in plasma LPS levels to 0.066 +/- 0.01 ng.ml-1 before heat-stress and 0.03 +/- 0.01 ng.ml-1 at Tr 44.4 degrees C just before primate demise. The mean arterial pressure of the control group was lower than the treated group for any given Tr; between Tr 42-43 degrees this difference was significant (p less than 0.05). Moreover, the cardiovascular parameters began to deteriorate at a lower Tr in the control group.