| Project/Area Number |
16500431
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| Research Category |
Grant-in-Aid for Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
Sports science
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| Research Institution | Kobe Design University |
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Principal Investigator |
KOGA Shunsaku Kobe Design University, Graduate School, Professor (50125712)
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| Co-Investigator(Kenkyū-buntansha) |
FUKUBA Yoshiyuki Prefectural University of Hiroshima, Faculty of Human Culture and Science, Professor (00165309)
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| Project Period (FY) |
2004 – 2005
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| Project Status |
Completed (Fiscal Year 2005)
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| Budget Amount *help |
¥3,600,000 (Direct Cost: ¥3,600,000)
Fiscal Year 2005: ¥1,700,000 (Direct Cost: ¥1,700,000)
Fiscal Year 2004: ¥1,900,000 (Direct Cost: ¥1,900,000)
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| Keywords | oxygen consumption kinetics / single myocite / PO2 / phosphorescence quenching / thermal dependence / 温度依存性 / Phosphorescence quenching |
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| Research Abstract |
This study determined the effect of temperature on the onset kinetics of intracellular PO2 (PiO2) in contracting isolated single muscle cells. Isolated Xenopus myocytes (n=6) performed moderate intensity contractions (0.167-0.5Hz, depending on fiber type) at normal (N; 20.5 ± 0.2℃) or high (H; 25.9 ± 0.2S℃) temperature for 2-3.5 min. Both N and H conditions were conducted by each fiber in randomized order. Peak tension and PiO2 (porphyrin phosphorescence quenching) were measured continuously. Peak tension in the H group was not different from N throughout the trial (p>0.05). However, the speed of the fall in PiO2 at the onset of contractions (t63; time to 63% of △PiO2) was significantly faster in H (57 ± 5 sec) vs. N (80 ± 10 see; p<0.05). Additionally, △PiO2 (mmHg) was 75% greater in the H group vs. N (p<0.05). The faster on-kinetics of oxidative phosphorylation (t63) demonstrate that a 5.4℃ increase in temperature allows muscle to more rapidly activate mitochondrial oxidative phosphorylation in response to a given signal of activation (i.e., similar tension profiles), possibly the result of priming the limiting reactions of oxidative phosphorylation. Our results suggest that warmer muscle will reduce the requirement for anaerobic energy production at the onset of exercise. Although more rapid onset kinetics of oxidative phosphorylation do not appear to affect the rate of fatigue onset (assessed as the relative fall in tension in isolated muscle preparations over a wide range of temperatures in the present study (data not show) and previous studies Lannergren (Blomstrand, Larsson, et. Al. 1985; Lannergren and Westerblad 1988), it is possible that the more rapid onset kinetics may a contributing factor in the more rapid time course of recovery from fatigue observed at higher muscle temperatures (Lannergren and Westerblad 1988).
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