In 63 mongrel dogs, microangiographic study was performed both immediately and two months after removal of 10th, 20th, 30th, 40th, 50th, and 60th day unilateral ureteral ligation.
The results were as follows:
1. The poor vascularity or shrinkage of cortical glomeruli was observed in all groups immediately after removal of obstruction, and returned to normal in the 10th, 20th, and 30th groups two months after removal of the obstruction. Its disappearance was observed in the 40th and later groups both immediately and two months after removal of the obstruction, and the change became more intense in the 50th and 60th day groups.
2. The poor vascularity or shrinkage of juxtamedullary glomeruli was observed in the 30th day and later groups immediately after removal of the obstruction. Its disappearance was observed in the 40th day and later groups immediately after removal of the obstruction, and did not recover two months after removal of the obstruction.
3. The spiralling of vessels was observed in rectal arterioles in the 10th day group and both in afferent arterioles and interlobular arteries in the 20th day group immediately after removal of the obstruction. These changes progressed gradually with duration of the obstruction. Two months after removal of the obstruction, the spirallings of both rectal arterioles and afferent arterioles were not seen up to the 30th day group, and the spiralling of interlobular arteries was not seen up to the 20th day group.
4. The stretching was observed in both arch form arteries and interlobar arteries in 30th day and later groups immediately after removal of the obstruction, and changed into spiralling two months after removal of the obstruction.
5. The diameter of intrarenal vessels, i.e. afferent arterioles, interlobular arteries and interlobar arteries, decreased to about 90% in the ratio of width to the opposite in 10th day group immediately after removal of the obstruction. This value of ratio gradually decreased with duration of the obstruction, and reached to about 60-70% in 50th, and 60th day groups immediately after removal of the obstruction. Two months after removal of the obstruction, a considerable recovery of the ratio was proved in these vessels up to the 40th day group.
6. The rectal arterioles converged to the tip of the papilla as if they straped the tail portion of curtain, but they were neither narrowed nor disappeared.
7. The comparison of the above mentioned microangiographic findings between immediately and two months after removal of unilateral ureteral obstruction suggests that the limit of recovery from renal blockade is 40 day ureteral obstruction.