[Studies on experimental renal damage in rats. I. Analysis of urinary alkaline phosphatase (author's transl)]

The experiment was undertaken to make a discrimination between glomerulonephritis (GN, Masugi-type) and tubular damage (TD, cephaloridine-induced) in rats by means of urinary alkaline phosphatase (AlP). Urinary AlP concentrations were increased 13 times in GN rats amd 8 times in TD rats, in comparison with the corresponding controls. Cellulose acetate plate electrophoresis before and after neuraminidase digestion revealed that urinary AlP from GN rats migrated similarly to serum and intestinal AlP, while the mobility of urinary AlP from TD rats resembled that of the kidney. The sensitivity of urinary AlP from GN to the inhibitors, L-phenylalanine and urea, was almost equivalent to that of intestinal AlP, and the sensitivity of urinary AlP from TD rats was similar to that from kidney AlP. Histochemically, AlP activity in the kidney appeared normal in GN rats, but it was markedly decreased in TD rats. Those results suggest that the urinary AlP from GN rats is identical to serum AlP originating from intestines, i.e., a selective increase in glomerular permeability in disturbed glomerular filtration occurs. On the other hand, urinary AlP from TD rats originated mainly from the kidney due to the disquamation in the proximal convoluted tubular epithelia. Thus the properties of urinary AlP are important for estimating the site of renal damage.