Transvascular protein movement in the intact ischemic hindlimb

Postischemic limb swelling following reperfusion may be related to microvascular changes associated with ischemia. We used lymph-to-plasma total protein concentration ratios (L/P) and lymph flow (QL) as an index of transvascular exchange in the intact dog hindlimb during steady state (C) (1 hr), ischemia (I) (6 hr), and reperfusion (R) (3 hr). Central pressures, femoral arterial and venous pressures (PA, PV) and QL were recorded every 15 min. Lymph was collected from a femoral lymphatic in the passively flexed leg (50 cycles/min). Three groups of animals were studied: GI, sham-operated (N = 5); GII, moderate ischemia (N = 7, PA = 30-45% C); and GIII, severe ischemia (N = 7, PA = 5-20% C). In GI, QL gradually increased over 10 hr without change in L/P. Moderate ischemia produced a decrease in QL, 3.55 +/- 2.02 mg/hr to 0.92 +/- 0.53 mg/hr (P less than 0.0001), and QL remained below baseline during R with no change in L/P over the 10 hr. Severe ischemia produced a similar decrease in QL, 1.91 +/- 2.05 mg/hr to 0.15 +/- 0.1 mg/hr (P less than 0.01); however, an increase to 2.56 +/- 2.14 mg/hr occurred during R. Severe ischemia increased L/P 0.42 +/- 0.08 to 0.64 +/- 0.23 (P less than 0.001) and remained elevated during R at 0.63 +/- 0.18 (P less than 0.001). An increase in the wet-to-dry weight ratio of ischemic to nonischemic muscle after reperfusion was noted only in GIII, 3.82 +/- 1.17 vs 2.60 +/- 0.45 (P less than 0.04). Severe ischemia produces changes in vascular integrity which augment protein flow. Prevention of these vascular changes may help to minimize the muscle swelling of reperfusion.