Ultrastructural changes in striated muscle after experimental tourniquet ischaemia and short reflow

The effect of experimental tourniquet ischaemia on the fine structure of a rabbit's hind limb striated muscle was studied. The tourniquet time varied from 1 to 4 h. Samples were obtained from the tibialis anterior muscle 30 min after releasing the tourniquet, the contralateral limb serving as the control. As the first sign of ischaemia, dilatation of the sarcoplasmic reticulum was observed after a tourniquet blockade of 1 h. After 4 h ischaemia myofibrillar components showed advanced degeneration. Ultrastructural alterations were distinct in the mitochondrial morphology. After 2 h, the mitochondria showed moderate but clear condensation. After 3 h many mitochondria showed high amplitude swelling and structural disorganization. Total blockade of the limb circulation up to 4 h effects the energy-producing organelles in the first place, especially sarcoplasmic reticulum, T tubules and mitochondria prior to the alterations in myofilaments. Ischaemia extended up to 3 h induces sublethal damage to the muscle cells.