The renal lesion associated with hemoglobinemia: a study of the pathogenesis of the excretory defect in the rat.

The role of renal ischemia in the pathogenesis of the renal failure produced by hemoglobin injection in the rat is evaluated. The data indicate that in the initial hours of this lesion renal blood flow is consistently reduced and that during its subsequent evolution blood flow rises towards normal levels, in some animals, while inulin clearance remains severely depressed. Volume expansion during the initial stage of the lesion may effect a rise in renal blood flow to normal levels with little effect on inulin clearance rate, further demonstrating the relative lack of dependence of the excretory defect on concomitant renal ischemia. These observations indicate that renal ischemia is probably a necessary factor in the initial production of the lesion; that it persists during its initial phase, up to 24 hours in most rats; and that, although it may contribute to the observed excretory defect, it is not the predominant etiologic factor. Other functional data indicate that renal blood is perfusing nephrons in which the excretory capacity is impaired but which retain the ability to extract Diodrast from the peritubular capillaries. This functional pattern indicates an excretory defect secondary either to intratubular obstruction or to a primary reduction of glomerular filtration rate of undefined etiology. The morphological findings of numerous dense intratubular hemoglobin casts and, in the well-perfused kidney, dilatation of proximal tubules, are suggestive of an obstructive lesion. However, the data do not conclusively distinguish between these two pathogenetic mechanisms.