Evaluation of interaction enthalpy between water and myoproteins in skeletal muscle for theoretical interpretation of MR signals

2021 Fiscal Year Final Research Report

• Project/Area Number: 19K17180
• Research Category: Grant-in-Aid for Early-Career Scientists
• Allocation Type: Multi-year Fund
• Review Section: Basic Section 52040:Radiological sciences-related
• Research Institution: Jikei University School of Medicine
• Principal Investigator: Nakahara Naoya 東京慈恵会医科大学, 医学部, 助教 (10632193)
• Project Period (FY): 2019-04-01 – 2022-03-31
• Keywords: DSC / 水 / 骨格筋 / MR信号

Outline of Final Research Achievements

Magnetic resonance images reflect not only water content but also water states in physiological tissue. Although water states in the tissue are not clarified yet in detail, interaction between water and macromolecules is generally considered to restrict motional freedom of the water molecules similarly to the freezing of water. As is the case with melting of ice, differential scanning calorimetry (DSC) can represent the restriction as extra heat absorption. DSC measurement with skinned fibers of the sartorius muscle from bull frogs at a rigor condition showed extra heat absorption at -24, -21, and 0 ℃. The extra heat absorption at -24, -21 ℃ reflected the intracellular states of actin and myosin. Integrated heat capacity in the range from -80℃ to 20℃ was decreased by denaturation or removal of actin. These results suggest that actin and myosin independently and cooperatively restrict surrounding water and that extra integrated heat capacity mainly depends on actin filaments.

Free Research Field

骨格筋生理学

Academic Significance and Societal Importance of the Research Achievements

従来のMR信号での解析では水分子の集団としてのふるまいを検出することは可能であったが、水分子間相互作用をエネルギーとしての評価をすることは困難であった。本研究で行ったDSCによる評価は水分子間相互作用をエネルギーとして評価するだけでなく、その水分子の局在まで明らかにできた。これらの研究を進めていくことで、生体内の水分子の相互作用エネルギーとMR信号の対応付けを行うことで、MR画像を理論的な解釈が可能なものにしていく一助になると考えられる。