Effects of a soft diet and hypothyroidism on the oxidative capacity of the masseter muscle fibers of the young Japanese field vole Microtus montebelli.
Effects of a soft diet (reduction in mastication activity: an exogenous factor) and hypothyroidism (endogenous factors) on the oxidative capacity of the masseter muscles in the young Japanese field vole Microtus montebelli, consisting only of fast-twitch oxidative (FO) fibers in the adult vole, was investigated histochemically and electron microscopically. Oxidative enzyme activity and mitochondrial development in the muscle fibers were not affected by a soft diet, while they were suppressed by doses of propylthiouracil (PTU) (hypothyroidism). Thus, it was suggested that acquisition of the sustained contraction ability in the masseter muscles of the young vole is induced by the endogenous factors rather than the exogenous factor.
Sugasawa
K
K
Zoological Laboratory, Faculty of Agriculture, Kyushu University, Fukuoka, Japan.
Mori
T
T
D000818:Animals; D003411:Arvicolinae / Q000502:physiology*; D004032:Diet; D007037:Hypothyroidism / Q000662:veterinary*; D008406:Masseter Muscle / Q000502:physiology*; D009119:Muscle Contraction; D010101:Oxygen Consumption