Fig. 1.

A–F: median sagittal sections (trichrome stain) of completely and partially obstructed kidneys. +/+, Wild-type; −/−, inducible nitric oxide synthase (iNOS) knockout. A and B: 7-day-old mice with complete unilateral ureteral obstruction (UUO). C and D: 7-day-old mice with partial UUO. E and F: 21-day-old mice with partial unilateral ureteral obstruction. Regardless of the age or degree of obstruction, the wild-type kidneys exhibit severe hydronephrosis. Although complete obstruction results in similar hydronephrosis in iNOS knockout kidneys (B), after partial obstruction (D and F) much of the parenchymal thickness is retained. Yellow lines denote measurements of parenchymal thickness at either pole and at the midsagittal point, from capsule through outer medulla (A and E). G and H: terminal transferase-dUTP-nick-end labeling staining showing apoptotic cells in both tubular epithelial cells and interstitial cells of 7-day-old mice with complete UUO; apoptosis is far more pronounced in iNOS [−/−] (H) than wild-type mouse (G). Scale bar = 100 μm (G and H). I: peristaltic rate related to renal pelvic diameter in 7-day-old animals with partial UUO. There was an increase in ureteral peristaltic rate in iNOS −/− compared with wild-type mice in relation to the renal pelvic diameter (2-way ANOVA, P < 0.05).