The effect of hypothermia on changes in isometric contractile function in skeletal muscle after tourniquet ischemia.

The effect of hypothermia on changes in contractile function of skeletal muscle observed after an episode of tourniquet ischemia has been investigated. Male Wistar rats were subjected to 2 hours of unilateral hypothermic (n = 33) or normothermic (n = 39) pneumatic tourniquet ischemia of a hind limb. Isometric contractile function was measured bilaterally from the gastrocnemius muscles after 1, 7, 14, 28, or 42 days of recovery. Compared to muscle subjected to normothermic ischemia, muscle that underwent hypothermic ischemia demonstrated more twitch tension at 1 day postischemia, higher maximum tetanic tension at all time periods, including 6 weeks after ischemia, and greater muscle weight at 6 weeks. Rat gastrocnemius muscle function is much better 1 day to 6 weeks after 2 hours of hypothermic ischemia than after 2 hours of normothermic ischemia. The results thus document the benefit of hypothermia during tourniquet ischemia in preventing or minimizing the changes in isometric contractile function observed after normothermic ischemia.