Evaluation of the Progress of Drug-induced Renal Disorder by Using Urinary Enzyme in Rats

Abstract

This study was performed to detect the progress of gentamicin-induced renal disorder by measuring the urinary enzyme N-acetyl-β-D-glucosaminidase (NAG) in rats. Twenty-one rats weighing 235 to 255g were divided into two groups : a gentamicin (GM) group and a control group. GM is an aminoglycoside that is known to have renal toxicity, and urinary excretion of NAG can indicate the degree of renal disorder caused by aminoglycosides. The GM group consisted of 14 rats, which were given GM at 50mg/kg B.W./day for seven days. The control group consisted of seven rats, which were given the same volume of saline on the same days as the GM group. In the GM group, serum creatinine (Cr) and urea nitrogen (UN) increased on day 7. In the GM group, on day 2, when renal function was still judged to be normal, there was a tendency for urinary excretion of NAG to increase transiently, but it recovered after a period of time. When urinary excretion of NAG did not recover, the renal disorder was judged to be severe. Conventionally, NAG evaluation using 24-hour urine sampling technique is thought to be preferable. But in this study, 24-hour evaluation could not detect the stage prior to renal failure. We suggest that NAG levels should be measured just before agents with renal toxicity are administered, in order to be able to evaluate the severity of renal disorder.