STUDIES OF THE EFFECT OF LARGE DOSES OF BACTERIAL PYROGEN IN THE DOG: 2. AN EXPLANATION FOR THE URINE DILUTION

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Abstract
Previous studies with large IV doses of bacterial endotoxin in dogs have shown this material to cause a diuresis which is uniformly associated with a rise in total renal blood flow, increased solute excretion, and a fall in Uosm unresponsive to ADH. The present study has demonstrated that renal cortical tissue sodium concentration is unaffected by endotoxin whereas renal sodium concentration of outer and inner medullary portions showed a striking fall. Endotoxin-treated kidneys were compared to their respective paired control (no endotoxin). It is postulated that the rise in total renal blood flow, following endotoxin, is mainly medullary and causes a washout of medullary interstitium multiplier deposited sodium. The efficiency of the renal counter current exchanger is impaired and tubule to interstitium gradient reduced. This would account for observed falls in Uosm and relative unresponsiveness to ADH after endotoxin.