| Project/Area Number |
63480092
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| Research Category |
Grant-in-Aid for General Scientific Research (B)
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| Allocation Type | Single-year Grants |
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| Research Field |
Applied veterinary science
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| Research Institution | Hokkaido University |
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Principal Investigator |
OHGA Akira Hokkaido University, Faculty of Veterinary Medicine, professor, 獣医学部, 教授 (10001512)
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| Co-Investigator(Kenkyū-buntansha) |
OHTA Toshio Hokkaido University, Faculty of Veterinary Medicine, instructor, 獣医学部, 助手 (20176895)
ITO Shigeo Hokkaido University, Faculty of Veterinary Medicine, associate professor, 獣医学部, 助教授 (40109509)
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| Project Period (FY) |
1988 – 1989
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| Project Status |
Completed (Fiscal Year 1989)
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| Budget Amount *help |
¥7,100,000 (Direct Cost: ¥7,100,000)
Fiscal Year 1989: ¥1,200,000 (Direct Cost: ¥1,200,000)
Fiscal Year 1988: ¥5,900,000 (Direct Cost: ¥5,900,000)
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| Keywords | Stress syndrome / Skeletal muscle / Skinned fiber / Ca-induced Ca release / Dantrolene / Adrenal medulla / Adrenal cortex / Pituitary / ストレス症候群ブタ / 骨格筋硬縮 / 筋小胞体 / ハロセン / カフェイン |
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| Research Abstract |
Pig stress syndrome (PSS) is a heredity disease which is characterized by muscle rigidity and high fever. This work was performed to elucidate the cause of muscle rigidity in PSS and determine the therapeutic action of dantrolene by using a single skinned skeletal muscle fiber.
In addition, we examined the effect of stress on plasma hormone levels in guinea-pigs.
1. The etiology of the muscle rigidity in PSS skeletal muscle.
The rate of Ca uptake by the sarcoplasmic reticulum (SR) and the Ca sensitivity of the contractile machinery of a PSS muscle fiber were not different from those of normal fibers. In the muscle of PSS, the rate of Ca-induced Ca release from SR was significantly higher than in a normal muscle fiber. Halothane potentiated the Ca-induced Ca release mechanism of the PSS muscle in a dose dependent manner.
2. The mechanism of the inhibitory action of dantrolene on skinned skeletal muscle.
Dantrolene inhibited the Ca-induced Ca release from SR at a high (38ﾟC) but not at a low temperature (20ﾟC). Ca uptake into the SR and the Ca sensitivity to the contractile machinery were not affected by dantrolene at 38ﾟC and 20ﾟC.
3. Changes in plasma concentrations of stress-related hormones in response to motion stimuli.
Guinea-pigs were cannulated chronically to examine the effects of motion stimuli on circulating stress-related hormone levels. Motion stress increased the plasma levels of noradrenaline, cortisof and ACTH, but not adrenalin. These results indicate that the motion stimuli preferentially activate the sympathetic nervous system and the pituitary-adrenal cortical system but not adrenal medulla.
These results suggest that the muscle rigidity of PSS is due to enhancement of Ca-induced Ca release mechanism in SR and dantrolene exhibits its therapeutic action by selective inhibition of this mechanism. The concentrations of stress-related hormones may be good indexes of stress conditions.
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