Abstract
We observed spin-spin relaxation process of 1H-NMR signals from suspension of myofibrils prepared from rabbit psoas muscle. As was the case in tissue skeletal muscle, decomposition analysis of the relaxation process could be well represented by the summation of several exponentials indicating that water molecules in the suspension could be conveniently grouped into several components based on the relaxation time constant (T2). The slowest two components dominated over faster relaxation components at the myofibril concentration ranges studied. With increase in the concentration of myofibrils, water component that relaxed with T2 around 0.15 s progressively replaced the slowest component of T2 > 0.4 s. An equivolumic point for these two components was found at 12 mg/ml myofibril concentration at 20°C in the absence of MgATP. Water components that relaxed more rapidly existed at small fractions. Since the average separation between the myofibrils is estimated to be 1.72 μm at the myofibril concentration of 10 mg/ml, myofibril affects water molecules within a significant distance from its surface differently from water molecules in the bulk solution. [Jpn J Physiol 55 Suppl:S121 (2005)]
