著者

Hisashi Naito Toshinori Yoshihara Ryo Kakigi Noriko Ichinoseki-Sekine Takamasa Tsuzuki

出版者

The Japanese Society of Physical Fitness and Sports Medicine

雑誌

The Journal of Physical Fitness and Sports Medicine (ISSN:21868131)

巻号頁・発行日

vol.1, no.1, pp.125-131, 2012-05-25 (Released:2012-08-22)

参考文献数

61

被引用文献数

9 10

---

Many researchers have been interested in the effects of heat stress on skeletal muscle. Recently, it has been demonstrated that heat stress on skeletal muscle results in an increase in muscle protein mass and subsequent muscle hypertrophy, and attenuation of muscle atrophy. Although the cellular mechanism remains unclear, it is thought that heat shock proteins (HSPs), which are highly conserved proteins induced by heat stress, play a major role in these phenomena. However, new insights suggest that heat stress-induced muscle hypertrophy and the prevention of muscle atrophy may be regulated not only by elevated HSP expression but also by multiple signaling pathways associated with protein synthesis and breakdown. Additionally, heat stress seems to cause various changes in other muscle functions. Although further studies are required to reveal the molecular biological mechanisms involved in the heat stress-induced changes in skeletal muscle, heat stress may be a useful tool for increasing muscle mass, attenuating disuse skeletal muscle atrophy, facilitating an early recovery from muscle damage, and improving glucose metabolism. This paper reviews studies of these effects of heat stress on skeletal muscle.

著者

TOMOHIRO NAKAMURA RYO KAKIGI NORIKO ICHINOSEKI-SEKINE TAKAMASA TSUZUKI HIROYUKI KOBAYASHI KAZUHIKO SAKUMA HISASHI NAITO

出版者

The Juntendo Medical Society

雑誌

順天堂醫事雑誌 (ISSN:21879737)

巻号頁・発行日

pp.JMJ19-OA08, (Released:2019-09-25)

参考文献数

21

---

Objective: Alpha-actinin (ACTN) 3 R577X polymorphisms have three genotypes: RR, RX and XX. Only RR and RX genotypes express ACTN3 protein in type II fibers. The purpose of this study was to clarify whether there are differences in ACTN3 protein expression levels and myosin heavy chain (MyHC) composition between RR and RX genotypes in Japanese college-level male sprinters.Materials and Methods: Forty-three Japanese college-level male sprinters participated in this study. Subjects were genotyped for ACTN3 R577X using a real-time polymerase chain reaction assay. Furthermore, muscle biopsies from the vastus lateralis muscle were obtained from a subset of subjects who had R allele and gave their consent (4 RR and 9 RX). ACTN3 protein expression levels were assessed by western blotting. MyHC composition was determined by sodium dodecyl sulfate polyacrylamide gel electrophoresis.Results: There was no difference in 100-m sprint performance among RR, RX and XX genotypes in all 43 subjects. In 13 biopsy-sampled subjects, there was also no difference in 100-m sprint performance between RR and RX and ACTN3 protein expression levels tended to be higher in RR genotype than in RX genotype. Although there were no differences in the proportion of type I and II MyHC isoforms between both genotypes, RR genotype had a significantly higher proportion of type IIx MyHC isoform and a significantly lower proportion of type IIa MyHC isoform than RX genotype.Conclusions: ACTN3 protein expression levels and the proportion of type IIx MyHC isoform are higher in RR genotype compared with RX genotype in Japanese college-level male sprinters.