No increasing injury during early reperfusion of skeletal muscle

Early reperfusion is thought to contribute to the final parenchymal and microvascular injury after transient ischaemia of skeletal muscle. Albumin, a large molecule which is not found in intact cells, can be used as an early marker of extensive membrane injury. In the present study, staining of intracellular albumin was used to test the hypothesis that muscle cell injury increases during early reperfusion. Complete ischaemia was induced for 3 h 15 min in rat hindlimbs. A total of 16 animals were randomized into two groups. The anterior tibial muscles were dissected and fixed in formaldehyde without reperfusion in one group, while circulation was re-established in the hindlimbs for 3 h in the other group. Cross-sections from the muscles were stained with antisera against rat albumin, using fast red as chromogen. This immunostaining showed a central zone of injured cells in each cross-section. The albumin-positive areas, calculated as a percentage of the total cross-sectional areas were 76 and 77% in the two groups respectively. This difference was not significant, suggesting that ischaemia and not reperfusion was the major trauma.