Transvascular albumin flux in rabbit hindlimb after tourniquet ischemia.

Transvascular clearance of labeled rabbit albumin was measured in gastrocnemius muscle and heel skin from anesthetized rabbits after 1 or 2 h of tourniquet ischemia. Albumin clearance, calculated as a 1-h extravascular uptake, was 4.7 +/- 0.4 and 29 +/- 1 microliter.h-1 x g dry wt-1 for control gastrocnemius muscle and heel skin, respectively. During the first hour of reperfusion, the clearance was 101 +/- 23 and 56 +/- 6 microliters.h-1 x g dry wt-1 in the muscle and skin, respectively. The clearance in skin during the second and third hour of reperfusion was not different from control. The increased clearance in muscle persisted during 2 h of reperfusion but returned to control levels during the third hour of reperfusion. The solvent drag reflection coefficient was measured by increasing venous pressure during reperfusion in one leg after bilateral ischemia. In skin, the reflection coefficient, calculated as 1 minus the change in clearance divided by the change in water weight, was 0.94 +/- 0.05 and did not change with tourniquet ischemia. The reflection coefficient in muscle was 0.98 +/- 0.01 for control animals and decreased to 0.66 +/- 0.11 during the first hour of reperfusion. The reflection coefficient was not different from control during the third hour of reperfusion. The transitory increase in microvascular permeability to albumin in skeletal muscle is more indicative of an acute inflammatory response than of endothelial injury.