The influence of available fluid on the production of experimental hemoglobinuric nephrosis in rabbits

Effects of proteinuria on the kidney; proteinuria, renal enlargement, and renal injury consequent on protracted parenteral administration of protein solutions in rats

Repeated intraperitoneal injections twice daily of various proteins into young rats were regularly accompanied by an increase in the protein content of the urine, significant renal enlargement, and often some degree of renal pallor. The most marked changes were induced by gelatin, followed in order by human albumin and bovine globulin. Rat serum produced similar but less conclusive changes. Similar changes were not produced by equivalent amounts of urea or casein hydrolysate. In sections from the kidneys of animals receiving gelatin, the cells of the convoluted tubules appeared enlarged, and they contained clear "spaces" throughout the cytoplasm. The tubular cells of the animals receiving the other solutions were not obviously altered in size or shape, and the cytoplasmic changes were slight or absent. There was little evidence of increased multiplication of cells or of tubular dilatation in the kidneys of any of the groups. Changes in concentrations of plasma proteins and hemoglobin, and the results of preliminary studies of the injected proteins in urine and renal tissue following the injections, are described and their possible significance discussed. It appears that the renal enlargement, as well as the increase in proteinuria and the tubular alterations which followed the protein injections, might have been caused in part by effects on the kidney of protein molecules per se, perhaps most likely by the effects on the tubular cells of an increased amount of protein filtered through the glomerular membranes, rather than entirely by effects of products of protein digestion and metabolism reaching the kidney through the blood stream. In the majority of animals there was no evidence from the morphological or functional studies, that the prolonged and continuous proteinuria induced by the protein injections resulted in renal damage, unless the renal enlargement, and the cytoplasmic changes which occurred regularly with gelatin, are considered evidence of damage. Renal enlargement and proteinuria promptly regressed after injections were discontinued. Lesions characterized by severe degrees of tubular damage, possibly as a result of tubular plugging, were observed in some of the animals of one group receiving gelatin solution of the usual concentration, and dilatation of renal tubules and glomerular capsules was present in some other gelatin-treated animals autopsied after relatively brief injection periods. A description is also presented of lesions of remarkable character which developed in the kidneys of all the animals of one small group receiving homologous serum obtained from severely anoxic donors. The possible relationship between the renal changes in the protein-injected animals and certain alterations of the kidneys observed in diseases characterized by large amounts of protein in the urine, is considered.

The role of aciduria in the development of hemoglobinuric nephrosis in dehydrated rabbits

The effect of acid diets, fasting, and dehydration on the urine pH and the kidneys was determined in 11 control animals. Hyaline casts in the collecting tubules and interstitial medullary edema were observed in the 8 that survived. The test rabbits were subjected to the same treatment as the controls but, in addition, received 1.8 gm./kilo of intravenous homologous hemoglobin. Eleven of 18 animals died of hemoglobinuric nephrosis. The rabbits which died of hemoglobinuric nephrosis exhibited significant alterations in two or more of the following: kidney weight, pigment cast accumulation, and elevations of NPN. The theories which have been advanced to explain the pathogenesis of hemoglobinuric nephrosis are evaluated in the light of the present observations. It is proposed on the basis of them that antecedent tubular damage is of primary importance in the pathogenesis of hemoglobinuric nephrosis.

EXPERIMENTAL STUDIES IN ACUTE RENAL FAILURE. II. FINE STRUCTURE CHANGES IN TUBULES ASSOCIATED WITH RENAL FAILURE INDUCED BY GLOBIN

When purified human globin is injected intravenously into rats it produces acute renal failure characterized by tubular casts and oliguria. The globin is identifiable within vesicles and channels in the cytoplasm of the proximal tubules, through which it passes from lumen to basal side with no apparent serious effect on the cells. When a very minimal amount of globin is taken up by cells of the distal limb of Henle's loop or distal tubules (lower nephron), a markedly deleterious effect is apparent and the cells die within a short time. The mixture of cell debris and precipitated globin forms plugs within the confines of the basement membranes of the former distal limbs and distal tubules. After a number of lower nephrons are plugged a disruption of proximal tubules is found, which apparently results from the effect of back pressure in the obstructed nephrons. We suggest that any amount in excess of a low threshold of globin, either alone or combined with heme or related material, has a toxic effect on lower nephron cells. Once initiated, the toxic effect is not reversible and the resulting plug of debris and precipitate will occlude the lumen. If a sufficient number of nephrons are made non-functional the animal becomes anuric; otherwise it is oliguric. A high rate of urine flow will protect against the excess absorption of material and thus against acute renal failure.

The renal lesion associated with hemoglobinemia. I. Its production and functional evolution in the rat

A method is presented for the production of a reproducible and reversible renal lesion in the rat by the intravenous injection of a relatively small amount of homologous hemoglobin (40 mg/100 g body weight). Production of the lesion is dependent on prior water deprivation and its severity is related to the degree of dehydration. Ether anesthesia, at the time of hemoglobin injection, predisposes to a severe and reproducible functional defect in the dehydrated rat. In contrast, injection of hemoglobin during pentobarbital anesthesia results in a significant lesion only sporadically. The functional evolution of the lesion has been characterized by inulin clearance measurements. Functional impairment occurs abruptly, within 1 hr after hemoglobin injection, and persists unchanged over the ensuing several hours. Some increase in inulin clearance rate is usually observed at 24 hr after injection, but severe functional impairment persists. Between 24 and 72 hr, a considerable increase in inulin clearance rate occurs, so that only moderate restriction of excretory function is present at the latter time. A further moderate increase in inulin clearance rate is apparent at 7 days after hemoglobin injection, but some reduction in function. persisted in all rats studied at this time. Hemoglobinuria is slight or inapparent in animals manifesting the most marked depression of excretory function, indicating that a severe renal lesion may exist in the absence of visible urinary pigment. Hemoglobinemia is evanescent at the dosage used in this study. These observations suggest that clinical acute renal failure secondary to hemoglobinemia may readily go unrecognized and that this may be a more frequent association than is now appreciated.