Total and regional renal blood flow during complete unilateral ureteral obstruction.

Regional renal blood flow was investigated after 1, 2, 12 and 24 h of unilateral ureteral obstruction in rats. Total renal and cortical blood flow rates were determined by the microsphere technique and regional medullary blood flow by the 86-Rb extraction method. The kidneys were microdissected into cortex and medulla, which was further divided into the outer stripe and the inner stripe of the outer zone, and the inner zone. In the obstructed kidneys cortical blood flow increased by 33% after 1 h of obstruction, but was normalized after 2 h. After 12 and 24 h this flow was significantly decreased (55% and 65% of control respectively). The pattern of total renal blood flow was similar to that of cortical blood flow. In the outer stripe there was an initial increase (44%) after 1 h, but later no significant deviations from control values were found. After 1 h of obstruction the blood flows in the inner stripe and the inner zone were not significantly different from control values. A significantly decreased blood flow was seen in the inner stripe after 2 h (57% of control) and in the inner zone after 12 h (58% of control). A significant recovery of the blood flow had occurred in the inner stripe and the inner zone after 24 h of obstruction. In the contralateral, non-obstructed kidney no significant changes were found, besides an increased innerstripe blood flow after 24 h of UUO.