Growth plate height of uremic rats is influenced by severity and duration of renal failure

To understand the changes induced by uremia in the epiphyseal growth plate, two studies were performed in young rats. In study 1, the morphological features of the tibial growth cartilage of stunted rats with different degrees of reduction of renal function were analyzed 2 weeks after nephrectomy and compared with control rats. There was a negative (r=−0.549, P<0.05) correlation between serum urea nitrogen (SUN) concentrations and longitudinal growth rate. The heights (mean±SEM) of growth cartilage (564±32 vs. 366±9 µm) and its hypertrophic zone (321±25 vs. 157±6 µm) were greater (P<0.05) in uremic than control rats and were highly and positively correlated (r=0.604, P<0.03 and r=0.706, P<0.01) with SUN levels. In study 2, the time course of growth plate alterations was investigated in uremic rats sacrificed 1 (NX-1), 2 (NX-2), and 4 weeks (NX-4) after nephrectomy compared with their corresponding control animals (C-1, C-2, C-4). Growth cartilage and hypertrophic zone heights were greater in NX-2 (533±60 and 264±32 µm) than in C-2 (345±10 and 131±11 µm), with no significant differences in the other groups. This report shows that enlargement of the growth plate and its hypertrophic stratum is greatly, although not exclusively, influenced by the severity and duration of renal insufficiency.