Enzymuria and tubular proteinuria in diabetic rats: a 12-week follow-up study.
Various biochemical parameters of renal tubular function were examined for a period of up to 12 weeks in rats rendered diabetic by an i.v. injection of streptozotocin. Except for a statistically significant decrease in the urinary excretion of gamma-glutamyl-transpeptidase to 64% of control values, the urinary excretion of beta-N-acetyl-D-glucosaminidase, beta-galactosidase, alanine aminopeptidase, and lactate dehydrogenase significantly increases in diabetic rats to between 154% and 712% of control values. This increased enzymuria is not correlated to the marked polyuria induced by diabetes (r between 0.14 and 0.35, not significant). Enzymuria is also accompanied by a 10-fold increase in the urinary excretion of the low molecular weight protein beta 2-microglobulin while the excretion of albumin is not significantly modified, indicating impairment of tubular reabsorption in diabetic animals. Clearance studies reveal that the clearance of both beta 2-microglobulin and infused egg-white lysozyme are also increased. Finally the histopathologic examination of paraffin sections of the kidney show hydropic degenerescence and pycnosis of the tubular cells. It is concluded that early-stage diabetes results in tubular impairment and that the streptozotocin-rat model appears well suited to the study of these early signs of renal dysfunction.
Département de médecine du travail et d'hygiène du millieu, Faculté de médecine, Université de Montréal, Québec, Canada.
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S
Chouinard
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Viau
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E
Greselin
D000118:Acetylglucosaminidase / Q000652:urine; D000626:Aminopeptidases / Q000652:urine; D000818:Animals; D018826:CD13 Antigens; D003921:Diabetes Mellitus, Experimental / Q000652:urine*; D003928:Diabetic Nephropathies / Q000652:urine*; D005260:Female; D007684:Kidney Tubules / Q000503:physiopathology; D007770:L-Lactate Dehydrogenase / Q000652:urine; D011507:Proteinuria / Q000209:etiology*; D051381:Rats; D011919:Rats, Inbred Strains; D013997:Time Factors; D001613:beta 2-Microglobulin / Q000652:urine; D001616:beta-Galactosidase / Q000652:urine; D005723:gamma-Glutamyltransferase / Q000652:urine
D001613:beta 2-Microglobulin; D007770:L-Lactate Dehydrogenase; D005723:gamma-Glutamyltransferase; D001616:beta-Galactosidase; D000118:Acetylglucosaminidase; D000626:Aminopeptidases; D018826:CD13 Antigens