Synthesis and degradation of glomerular basement membrane in rats with nephrotoxic nephritis.

Degradation and synthesis of the collagen portion (CLP) of the glomerular basement membrane (GBM) in glomeruli of rats with nephrotoxic nephritis (NTN) were determined in vivo and in vitro. Degradation of CLP in rats with NTN was only increased during the first 24 h after induction of NTN. After 24 h, the half-life of CLP in NTN rats (16.9 days) was not significantly different from that in the controls 15.6 days). The loss of CLP during the first 24 h is accompanied by an increased synthesis, measured in vivo and in vitro. The increased synthesis, however, does not seem to be sufficiently high to result in accumulation of CLP-like material in NTN. Since degradation and synthesis of CLP was not altered during the later phase of NTN, it is unlikely that chronic proteinuria is the result of an ongoing abnormal turnover of CLP.