MILD HYPOTHERMIA PROTECTS AGAINST ISCHEMIA-REPERFUSION INJURY IN RABBIT SKELETAL-MUSCLE

In three groups of rabbits, the rectus femoris muscle was subjected to 4 hours of total ischaemia. In Group 1 (normothermia, n = 5) the core temperature was maintained within the range 36-38 degrees C for the d uration of ischaemia. In Group 2 (total hypothermia, n = 5) the core t emperature was allowed to fall to 31.5-33.5 degrees C. In Group 3 (mus cle only hypothermia, n = 5) core temperature was maintained as in Gro up 1 but the muscle temperature was allowed to fall to 29.5-31.5 degre es C. After 24 hours of reperfusion the muscles were harvested and mea surements made of muscle viability, oedema and myeloperoxidase content . The mean (s.e.m.) muscle viability of Group 1, 19.5 (3.8)%, was sign ificantly less than that of both Group 2, 86.0 (2.0)%, and Group 3, 87 (4.1)%, (P < 0.001). Muscle oedema and myeloperoxidase levels were el evated in all experimental groups, but differences were not significan t. These findings indicate that ischaemia-reperfusion injury in skelet al muscle in this model is highly temperature-sensitive, small reducti ons in muscle temperature during ischaemia providing significant prote ction against ischaemia-reperfusion injury.