A quantitative study of p38 mitogen-activated protein kinase on renal dysfunction after hemorrhagic shock in rats.

BACKGROUND

The severity of renal dysfunction correlates with fatal outcome after hemorrhagic shock. However, the precise mechanism for increasing renal dysfunction in response to the degree and the progression of hemorrhagic shock has not been clearly demonstrated. In this study, we examined the role of p38 mitogen-activated protein kinase (MAPK) activation on the progression of renal dysfunction by studying the differential severity of bleeding.

METHODS

Hemorrhagic shock was studied by quantitatively grading four groups of hemorrhaging rats: not hemorrhaged (Sham group); hemorrhaged up to 16.7% of their total body blood volume (16.7% group); hemorrhaged up to 25% (25% group); and hemorrhaged up to 33% (33% group). Mean arterial blood pressure and renal blood flow were recorded up to 5 hours after the bleeding. Kidneys were excised for assays of p38 MAPK and mRNA of the proinflammatory cytokines, such as tumor necrosis factor-α and interleukin-1β, and for histopathological study. The levels the cytokines and creatinine were measured in the renal venous blood.

RESULTS

As the amount of bleeding increased, the initial activation of p38 MAPK and the expression of renal cytokines were progressively enhanced. The severity of renal dysfunction, manifested by serum creatinine concentration, histologic damage score, and neutrophil accumulation in the kidney, was well correlated with the degree of initial p38 MAPK activation.

CONCLUSIONS

The increase of initial p38 MAPK activation after hemorrhagic shock quantitatively enhanced the ensuing renal dysfunction in response to the degree and the progression of hemorrhagic shock.