Influence of Age on the Compensatory Response in Growth and Function to Unilateral Nephrectomy 1

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.