[Effects of hypoxic acclimation on oxygen consumption of skeletal muscles in rats with frostbite]

Oxygen consumption of gastrocnemius in rats of frostbite at normoxia (FN), frostbite during acute hypoxia (FAH) and frostbite during hypoxia after hypoxic acclimation (FHAC) groups was investigated with a system of oxygen consumption measurement before and after the rats' right hind legs were frozen in order to provide theoretical data for exploring the reasons that hypoxic acclimation could aggravate tissue damage of animals wth frostbite.

Before freezing, oxygen consumption of gastrocnemius in rats of FHAC group decreased by 26.2%. At the first day after freezing, oxygen consumption of gastrocnemius in rats of FN, FAH and FHAC groups was 5.93 +/- 0. 66, 4.74 +/- 1.87 and 0.76 +/- 0.39 [kPa/(g x min)], and decreased by 76.3%, 77.9% and 95.9% respectively as compared with themselves before freezing, and that of FHAC group was much lower than those of FN and FAH groups. At the fifth day after freezing, oxygen consumption of gastrocnemius of the three groups returned to 62.8%, 44.9% and 28.8% of those themselves before freezing respectively, and that of FHAC group was much smaller than those of FN and FAH groups, showing that post-frostbite metabolic rate of skeletal muscle of rats acclimated to hypoxia decreased further and restored much slowly.

Both hypoxic acclimation and frostbite could decrease the oxygen consumption of gastrocnemius in rats, the complex of those two effects on oxygen consumption made the oxygen consumption to decrease further, suggesting that the changes in tissue metabolism could be one of the main factors that affected the degree of tissue damage and recovery.