Single-nephron adaptations to partial renal ablation in the dog.

Micropuncture and histological studies were performed in dogs to characterize single-nephron adaptations to partial renal ablation. Dogs underwent sham surgery (group 1, n = 6), three-fourths nephrectomy (group 2, n = 10), or seven-eighths nephrectomy (group 3, n = 6). Single-nephron glomerular filtration rate (SNGFR) was 71.0 +/- 4.2 nl/min in group 1, 132.5 +/- 9.6 nl/min in group 2, and 161.8 +/- 12.4 nl/min in group 3 (P less than 0.05). There were parallel increases in single-nephron glomerular plasma flow rate (GPF), with a mean value of 235.3 +/- 20.1 nl/min in group 1, 442.4 +/- 34.4 nl/min in group 2, and 569.6 +/- 73.7 nl/min in group 3 (P less than 0.05, group 1 vs. groups 2 and 3). Glomerular capillary pressure, estimated from the sum of proximal tubule stop-flow pressure and arterial oncotic pressure, was 63.2 +/- 1.9 mmHg in group 1, 73.5 +/- 2.0 mmHg in group 2, and 77.9 +/- 2.2 mmHg in group 3 (P less than 0.05, group 1 vs. groups 2 and 3). The mean glomerular transcapillary hydraulic pressure gradient (delta P) in group 2 was not different from group 1 (46.8 +/- 1.3 vs. 43.9 +/- 1.8 mmHg, NS); however, it was significantly increased in group 3 (50.0 +/- 1.4 mmHg; P less than 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)