Progressing alterations in transient ischemia of skeletal muscles: an ultrastructural study.

Ultrastructural muscle changes resulting from temporary anoxia and their evolution were studied in dogs. Ischaemia of the hind limb was produced by subcutaneous ligation of all muscles of the thigh and clamping of the femoral artery. Revascularization was obtained by declamping and removal of the muscle ligature. The period of ischaemia ranged from 4 1/2 to 7 h, the latter being the upper limit allowing functional recovery after revascularization. 6-7 h of ischaemia revealed focal degenerative changes of varied intensity. These consisted of enlarged mitochondria with ruptured cristae, small pads of glycogen granules and accumulation of lipid vacuoles. The tubules of sarcoplasmic reticulum contained dense, fine-granular material. Focal myofibrillar destruction and disruption of the Z line were encountered in half of the cases. The myofibrillar damage was more severe 9 days after revascularization of the muscles. The functional recovery of the ischaemic limbs in the present study may be due to the focal nature of these changes.