Minoru Fukuzaki

Intracellular and Extracellular Spaces of Normal Adult Rat Brain Determined from the Proton Nuclear Magnetic Resonance Relaxation Times

The nuclear magnetic resonance method was used to investigate the state of water molecules in normal rat brain tissue in vitro. The transverse magnetization decay curve (TMDC) of the fresh brain tissue of adult rats (8- or 10-weeks-old) was biexponential, which could be interpreted in terms of two distinct transverse relaxation times (T2). Several factors that may affect the TMDC are discussed. It was concluded that the fast and slow components of T2 correspond to those of the water molecules of the intracellular and the extracellular spaces of normal rat brain tissue, respectively.

Dynamic Behaviors of Solvent Molecules Restricted in Poly (Acryl Amide) Gels Analyzed by Dielectric and Diffusion NMR Spectroscopy

Dynamics of solvent molecules restricted in poly (acryl amide) gels immersed in solvent mixtures of acetone–, 1,4-dioxane–, and dimethyl sulfoxide–water were analyzed by the time domain reflectometry method of dielectric spectroscopy and the pulse field gradient method of nuclear magnetic resonance. Restrictions of dynamic behaviors of solvent molecules were evaluated from relaxation parameters such as the relaxation time, its distribution parameter, and the relaxation strength obtained by dielectric measurements, and similar behaviors with polymer concentration dependences for the solutions were obtained except for the high polymer concentration in collapsed gels. Scaling analyses for the relaxation time and diffusion coefficient respectively normalized by those for bulk solvent suggested that the scaling exponent determined from the scaling variable defined as a ratio of the size of solvent molecule to mesh size of polymer networks were three and unity, respectively, except for collapsed gels. The difference in these components reflects characteristic molecular interactions in the rotational and translational diffusions, and offered a physical picture of the restriction of solvent dynamics. A universal treatment of slow dynamics due to the restriction from polymer chains suggests a new methodology of characterization of water structures.

Molecular dynamics of aqueous solution of nonionic surfactant by broadband dielectric spectroscopy, dynamic light scattering, and PGSE-NMR

Molecular dynamics of pentaethylene glycol dodecyl ether (C12E5) aqueous solutions were studied by Broadband Dielectric Spectroscopy, Dynamic Light Scattering, and Pulse Gradient Field Spin-Echo method. C12E5 aqueous solutions showed dielectric relaxation processes that are due to cooperative motion of water molecules and C12E5 molecules. The relaxation process of water molecules is influenced by C12E5 molecules. Cooperative interactions between water molecules and C12E5 molecules become significant with increasing C12E5 concentration in hexagonal, cubic, lamellar, and reverse micellar structures. In the lamellar phase, a dielectric relaxation process due to interface polarization from an anisotropic structure was observed in the range of 100 kHz – 1 MHz. Translational diffusion of water molecules is affected by the lamellar structure observed by Pulse Gradient Field Spin-Echo method of Nuclear Magnetic Resonance. The mutual diffusion of C12E5 micelles is characterized by dynamic light scattering.

Suppression of Water Shift into Intracellular Space by TA-3090 (Calcium Entry Blocker) Measured with NMR

In order to clarify the effects of TA-3090 (calcium entry blocker) on the suppression of water after ischaemic events, 16 measurements of T2f were continuously performed on brain biopsy (for 2-60 min) obtained from treated and control Wistar rats. The time constant (k) and NMR parameters (T2f,(O) delta T2f, T2fmax(T2f(O) + delta T2f) were obtained from 16 values of T2f. The values of k in Wistar rats treated with intravenously administrated TA-3090 (0.5 mg/kg) were significantly prolonged as compared to that of control. There were no significant differences of maximum prolongation of T2f(T2fmax(T2f(O) + delta T2f) among three groups. Since the prolongation of T2f after biopsy reflects the water shift from extra to intracellular space, the increments of time constant indicates that TA-3090 suppresses the water shift into intracellular space. Our present results suggest that TA-3090 prevents some processes involved in irreversible cell damage and suppresses the cytotoxic brain oedema in the incomplete ischaemic area where non-competitive calcium channel is inactive.