Influence of Age on the Compensatory Response in Growth and Function to Unilateral Nephrectomy

The effect of age on the structural and functional response to unilateral nephrectomy was studied in weanling (group I) and young adult (group II) rats. Although compensatory growth in group I was not significantly greater than in group II one week following surgery (44% vs 39%, p - NS), after 4 wk renal mass had increased 144% in group I and 66% in group II (p < .0001). Glomerular filtration rate per unit kidney mass at 1 wk post surgery was 875 ± 92 (mean ± SEM) μ1/min/gKW) in group I and 1132 ± 67 in group II (p - NS) and at 4 wk was 1176 ± 67 in group I and 1261 ± 67 in group II (p - NS). These data indicate that the magnitude of compensatory growth in immature rats is greater than in adults and that functional adaptation parallels the structural change.