Evaluation of the Renal Toxicity of Heme Proteins and Their Derivatives: a Role in the Genesis of Acute Tubule Necrosis

This investigation studies the toxicity of heme proteins and/or their break-down products on renal function. Heme proteinemia precedes acute tubule necrosis at a frequency great enough to suggest a causal relationship between the two events. Physiological and metabolic functions of kidney slices are investigated in several models of acute tubule necrosis. Organic acid and organic base transport is depressed earliest. These alterations in tubule function cannot be explained by ischemia or obstruction alone. Heme proteinemia in rats or incubation of renal slices in medium containing heme proteins yields several interesting observations. Neither in vivo or in vitro do hemoglobin and methemoglobin alone produce a depressive effect on the transport systems studied. However, parallel to many clinical situations, when such secondary insults as hypoxia and elevated ammonia concentrations are included in the experimental design, transport functions are depressed. Ferrihemate, a molecule smaller than hemoglobin or methemoglobin, depresses transport function without secondary insults. From these studies it is concluded that heme proteins play a role in tubule dysfunction seen in acute tubule necrosis. A model is presented that collates these data with other factors known to play a part in the pathogenesis of this renal syndrome.