Possible role of calcineurin in heating-related increase of rat muscle mass.
The purpose of this study was to investigate the contribution of calcineurin-related intracellular signal for heat-stress-associated muscle hypertrophy. Wistar strain male rats (7-week-old) were randomly divided into four groups: (1) control (CC, n=15), (2) control with the injection of cyclosporine A (CsA) (CA, n=15), (3) heat-stressed (HC, n=15), and (4) heat-stressed with the injection of CsA (HA, n=15). The heat-stress groups (HC and HA) were exposed to heat (41 degrees C for 60 min) in a controlled heat chamber without anesthesia. Soleus and extensor digitorum longus (EDL) muscles were dissected and weighed 1, 7, and 14 days after the exposure. Wet and dry weights of soleus were increased 7 days following heat exposure. The expressions of heat shock protein 72 (HSP72) and calcineurin in both muscles were also increased within 1 and 7 days following heat-stress, respectively. Administration of CsA, a specific inhibitor for calcineurin, depressed heat-stress-associated increase of muscle weight and calcineurin expression, especially in soleus. These observations suggest that a calcineurin-dependent signaling pathway may play an important role in the heat-stress-related skeletal muscular hypertrophy. Application of heat-stress to skeletal muscles may be a useful tool to gain muscular mass and force generation not only in athletes, but also in patients during rehabilitation.
Kobayashi
Tetsuo
T
Department of Physiology, St. Marianna University School of Medicine, Kawasaki 216-8511, Japan.
Goto
Katsumasa
K
Kojima
Atsushi
A
Akema
Tatsuo
T
Uehara
Kenji
K
Aoki
Haruhito
H
Sugiura
Takao
T
Ohira
Yoshinobu
Y
Yoshioka
Toshitada
T
D000818:Animals; D001835:Body Weight; D019703:Calcineurin / Q000502:physiology*; D055551:HSP27 Heat-Shock Proteins; D006360:Heat-Shock Proteins / Q000378:metabolism; D006358:Hot Temperature; D018482:Muscle, Skeletal / Q000254:growth & development* / Q000378:metabolism; D009363:Neoplasm Proteins / Q000378:metabolism; D009929:Organ Size; D051381:Rats; D017208:Rats, Wistar
D055551:HSP27 Heat-Shock Proteins; D006360:Heat-Shock Proteins; C486114:Hspb1 protein, rat; D009363:Neoplasm Proteins; D019703:Calcineurin