Variation in the isoenzymes of N-acetyl-beta-D-glucosaminidase and protein excretion in aminoglycoside nephrotoxicity in the rat.

Three aminoglycosidic antibiotics: tobramycin, amikacin and sisomicin were administered to rats. There was an increase in the activity of N-acetyl-beta-D-glucosaminidase (NAG) excreted in the urine and this was characterized by a change in the isoenzyme profiles eluted from DEAE--cellulose. The largest increase in NAG activity was observed following sisomicin administration due mainly to an increase in the B-form of NAG with a concomitant fall in the intermediate (I-form). Separation of urinary proteins by SDS-polyacrylamide gel electrophoresis demonstrated a mixed tubular and glomerular proteinuria following administration of sisomicin. It is concluded that the separation of NAG isoenzymes and urinary proteins provides valuable additional information on the nature and severity of antibiotic nephrotoxicity.