抄録
It is well known that mechanical stress induces hypertrophy in skeletal muscles. However, molecular mechanisms responsible for muscular hypertrophy are still unclear. Muscle contraction, as well as mechanical stress on muscular cells, also increases the expression of heat shock protein 72 (HSP72, one of the stress proteins) in muscular cells. Increment in HSP72 expression is also induced by most types of cellular stresses, such as oxygen radicals, the reducing peripheral blood circulation and heat exposure. These observations suggest that some types of cellular stress may induce muscular hypertrophy. Recently, we have discovered heat stress-induced muscular hypertrophy in cultured skeletal muscle cells and in rat skeletal muscles. Evidences suggest that heat stress on muscular cells activates Akt/mTOR/p70S6K signaling pathway and facilitates the proliferation and differentiation of satellite cells. Adult skeletal muscle has a remarkable ability to regenerate following myotrauma. It has been reported that the regeneration of skeletal muscle is largely dependent on satellite cells. Therefore, heat stress-induced muscular hypertrophy may be induced by the activation of the cellular regenerative system in skeletal muscle cells. [Jpn J Physiol 54 Suppl:S55 (2004)]
