TIME-COURSE ANALYSIS OF SERUM AND URINARY PROTEINS BY SDS-PAGE IN EXPERIMENTAL NEPHROTIC SYNDROME

Serum and urinary proteins from rats with nephrotic syndrome (NS) indu ced by puromycin aminonucleoside (PAN) were analyzed by sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE). Analysis was m ade on days 2, 4, 6, 8, 10, 12, 16, 20, and 30 after PAN injection. Da ta were compared with control rats (C). Rats developed proteinuria on days 4-30 and hypoproteinemia on days 4-16. Total protein concentratio n in serum and urine was similar on day 6. SDS-PAGE revealed that urin ary albumin augmented on days 4-30 and serum albumin decreased markedl y on days 4-20. Albumin concentration in serum and urine was similar o n days 4-16. In addition, the study examined serum changes of 7 other proteins (designed as A, B, C, D, E, F, and G) which appeared or incre ased in urine, and whose molecular weights were higher (A, B, and C) o r lower (D, E, F, and G) than that of albumin. In serum, protein A rem ained unchanged; protein B and G increased; proteins C, D, E, and F de creased. The qualitative pattern of urinary proteins remained essentia lly unchanged on days 4-30. During the intense proteinuria, the serum concentrations of protein B and albumin were similar and the urine con centrations of proteins C and D became comparable to that found in ser um. These 7 serum proteins did not show the same behavior although all of them were excreted in urine. These data indicate that in PAN-nephr otic rats: (a) urinary proteins can be of low and high molecular weigh t, (b) serum proteins can be regulated independently of their urinary excretion and molecular weight, (c) the urine concentration of total p rotein and some specific proteins can reach values similar to that fou nd in serum during the intense hypoproteinemia, and (d) the qualitativ e pattern of urinary proteins was unrelated to the magnitude of protei nuria.