Hyperbaric Exposure with High Oxygen Concentration Improves Altered Fiber Types in the Plantaris Muscle of Diabetic Goto-Kakizaki Rats

Hyperbaric exposure with high oxygen concentration inhibits a growth-related increase in the glucose and insulin of diabetic rats. In this study, 5-week-old diabetic Goto-Kakizaki rats were exposed to a hyperbaric environment (1.25 atmospheric pressure) with a high oxygen concentration (36%) for 6 h daily. Fiber type distributions and oxidative enzyme activities in the fast-twitch plantaris muscle of Goto-Kakizaki rats were examined after hyperbaric exposure for 4 weeks. The percentages of high-oxidative type I and type IIA fibers increased and that of low-oxidative type IIB fibers decreased after hyperbaric exposure. Furthermore, the fiber oxidative enzyme activity increased after hyperbaric exposure, regardless of fiber type. It is concluded that altered patterns of fiber types in the plantaris muscle of diabetic rats shift toward normal, which is observed in nondiabetic rats, following hyperbaric exposure with high oxygen concentration.