| Project/Area Number |
62480108
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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 |
Neurophysiology and muscle physiology
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| Research Institution | 大分医科大学 |
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Principal Investigator |
YAMADA Kazuhiro Med.Col.Oita, Physiology, Professor, 医学部, 教授 (20053027)
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| Co-Investigator(Kenkyū-buntansha) |
YAMADA Naoko Med.Col.Oita, Physiology, assistant (1989), 医学部(平成元年度), 助手 (60101086)
TANOKURA Masaru Med.Col.Oita, Physiology, assistant (1987), 医学部(昭和62年度), 助手 (60136786)
KOMETANI Kaoru Med.Col.Oita, Physiology, associate Prof. (1987-1988), 医学部(昭和62、63年度), 助教授 (20107387)
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| Project Period (FY) |
1987 – 1989
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| Project Status |
Completed (Fiscal Year 1989)
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| Budget Amount *help |
¥6,600,000 (Direct Cost: ¥6,600,000)
Fiscal Year 1989: ¥800,000 (Direct Cost: ¥800,000)
Fiscal Year 1988: ¥1,000,000 (Direct Cost: ¥1,000,000)
Fiscal Year 1987: ¥4,800,000 (Direct Cost: ¥4,800,000)
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| Keywords | skinned muscle fiber / Ruby laser / caged ATP / ATP / muscle stiffness / cross-bridge / ethylene glycol / active tension of muscle / Caged ATP / 収縮の動力学 / エチレングリコール / ルビーレーザ / グリセリン処理筋 / アクトミオシン / リン核磁気共鳴法 |
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| Research Abstract |
Correlations between the mechanical and biochemical processes of muscle contraction, and the effect of the solvent on them, have been studied.
Skinned muscle fibers in the rigor state were incubated in a solution containing P^3-1(2-nitro)pherlethyl-ATP, 'caged ATP' an inert photolabile precursor of ATP, and free Ca^<2+> concentration of either <lO^<-8>M of -30 uM. The mechanical response of the fibers was recorded during relaxation, as well as during the active contraction, initiated by liberating ATP with a pulse of 347 nm light from a frequency-doubled ruby laser. When ethylene glycol was included in the solution to 10%, the transient rise of tension during relaxation reported by Goldman, Hiberd & Trentham (1984) was markedly suppressed. Stretching fibers before photolysis changed the time course of the early parts of the tension transients but with relatively less effect on the later phases or on stiffness.
The tension records from stretch and isometric trials converged to a final common time course of relaxation. Analysis of the convergence of tension records provided a means for measuring the cross-bridge detachment rate from the thin filament as a function of ATP concentration. The apparent second-order rate constant for detachment was at least 5xlO^5 M^<-1> s^<-1> at 20ﾟC, and this rate was the same in ethylene glycol. When Ca^<2+> was included the medium, active tension was produced. Analysis of the tension records in terms of sequential detachment and reattachment reactions, provided a measure of cross-bridge reattachment rate and an alternate measure of the detachment rate. The rate of cross-bridge reattachment leading to force production, as well as the steady active tension, was reduced to 70% in ethylene glycol. These results indicated that a solvent-protein interaction is involved in the cross-bridge reattachment and force generation.
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