The effect of temporary clamping of the renal vessels on the vascular resistance in rabbit kidneys.

In studies of 45 rabbits, either the renal artery (35 animals), or the renal artery and vein (10 animals) were clamped in situ. The effect of the clamping--of the warm ischemia--on the vascular resistance of the kidney after reestablishment of the circulation was examined in perfusion studies made after removal of the kidneys from groups of 5 animals between 1 and 5 days after revascularization. Resistance patterns were measured during hypothermic perfusion. The results confirm earlier findings that vascular resistance increases in proportion to the duration of warm ischemia up to 60 min, but not thereafter. The renal vascular resistance falls over the days following revascularization, more slowly after longer periods of ischemia. Thus after 60 min of warm ischemia the vascular resistance became normal within 24 hours, but after 180 min of warm ischemia, the normal resistance range was not reached until 96 hours after reestablishment of the circulation. When both the renal artery and the renal vein were clamped, the pattern was the same but much less emphatic. The vascular resistance never attained such high values as seen after clamping of the renal artery alone, and became normal after 24 hours of revascularization, even when the period of warm ischemia was as long as 180 min.