Escherichia coli endotoxin injections potentiate experimental ischemic renal injury

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Abstract
The purpose of this study was to assess the influence of Escherichia coli endotoxin on the evolution of ischemic acute renal failure (ARF). Rats were subjected to 25 min of bilateral renal artery occlusion (RAO) plus subcutaneous/intraperitoneal injections of either boiled E. coli or purified E. coli endotoxin (1.5 mg). Boiling the E. coli renders them nonviable but leaves endotoxin intact. Ischemic controls were injected with saline. The E. coli injections exacerbated ischemic ARF, doubling the degree of azotemia and increasing the extent of tubular necrosis and cast formation. This occurred without an adverse effect on renal blood flow or blood pressure during the initiation phase or maintenance phase of the ARF. Endotoxin tolerant rats were totally protected against the E. coli-ARF potentiating effect. Neither Staphylococcus aureus nor E. coli with denatured endotoxin adversely affected ischemic injury. Purified E. coli endotoxin reproduced the E. coli-ARF potentiating action. Neither E. coli nor purified endotoxin induced azotemia in the absence of renal ischemia. Conclusion: E. coli endotoxin can exacerbate ischemic renal injury without compromising renal hemodynamics. This action appears to be mediated by an adverse effect of endotoxin on critical subcellular determinants of ischemic tissue injury.