Rapid regeneration in postischaemic skeletal muscle with undisturbed microcirculation.

The regeneration of skeletal muscle cells was investigated in the extensor digitorum longus muscle (EDL) of rats subjected to hindlimb tourniquet ischaemia preceded by glycogen depletion. In this experimental model a distinct population of 'white' muscle cells are preferentially damaged, while there is minor damage to microvessels. A rapid regenerative response occurred after injury. Mitotic figures were obvious in satellite cells of damaged as well as of uninjured muscle cells within 48 h after the ischaemic insult. All debris of injured cells was phagocytized and removed within 72 h and replaced by clusters of myoblasts. Small immature muscle cells could be demonstrated within 96 h after injury. During the entire regeneration process the basic architecture of the muscle was preserved and surviving muscle cells were present among the regenerating ones. Histochemical investigations 3 weeks after injury revealed an increased number of 'red' muscle cells in the postischaemic EDL compared to the contralateral undamaged muscle. It is concluded that the described experimental model may be useful for studies on skeletal muscle regeneration.