SUBTOTAL NEPHRECTOMY - A MOSAIC OF GROWTH-FACTORS

We have studied the distribution of immunoreactive growth factors, by an avidin-biotin-peroxidase technique, throughout the course of progre ssive renal scarring in rats submitted to extensive renal ablation. Gr oups of rats (n=6) were sacrificed at Days 7, 15, 21, 30, 90 and 150 f ollowing subtotal nephrectomy (SNx) by ligation and resection of the r enal poles. During the early stages, when compensatory renal growth to ok place, increased renal immunostaining for insulin-like growth facto r-I (IGF-I) and epidermal growth factor (EGF) was detected within the collecting ducts and distal tubules, respectively. As renal scarring b ecame established by Days 90 and 150, these two growth factors were de tected within the cells of damaged and vacuolated distal tubules. By c ontrast, a progressive increase immunostain for platelet-derived growt h factor (PDGF)-AB was apparent within the glomeruli from Day 15 onwar d preceding the onset of glomerulosclerosis. A third staining pattern was apparent by Day 15 for transforming growth factor-beta (TGF-beta) and by Day 30 for IGF-I consisting of a perivascular and interstitial distribution coinciding with adventitial expansion and tubulo-intersti tial fibrosis, respectively. A mosaic of growth factors is expressed w ithin the kidneys of rats submitted to extensive renal ablation.