Biomedical subjects
R Natori
Publications and source records attributed to R Natori.
Connectin filaments link thick filaments and Z lines in frog skeletal muscle as revealed by immunoelectron microscopy.
In an earlier study connectin, an elastic protein of striated muscle, was found to be associated with "gap filaments" originating from the thick filaments in the myofibril, but it was not clear whether it extends to Z lines or not (Maruyama, K., H. Sawada, S. Kimura, K. Ohashi, H. Higuchi, and Y. Umazume, 1984, J. Cell Biol., 99:1391-1397). In the present immunoelectron microscopic study using polyclonal antibodies against native connectin, we have concluded that the connectin structures are directly linked to Z lines from the thick (myosin) filaments in myofibrils of skinned fibers of frog skeletal muscle. There were five distinct antibody-binding stripes in each half of the A band and two stripes in the A-I junction region. Deposits of antibodies were recognized in I bands and Z lines. We suggest that connectin filaments run alongside the thick filaments, starting from a region approximately 0.15 micron from the center of the A band.
Distilled water-induced contractions in dehydrated and skinned muscle fibers.
Dehydrated frog skeletal muscle fibers, prepared by simply immersing the muscle fibers in pure glycerol for 2-3 min, showed a marked sustained tension development in response to distilled water (DW). Similar DW-induced tension responses were also seen in mechanically skinned muscle fibers. The DW-induced mechanical responses were rapidly relaxed by a conventional relaxing solution. The marked reproducibility of the DW-induced responses, together with the simplicity of the dehydration procedure, indicates that the dehydrated fibers can be used as a substitute for the skinned fibers in studying the mechanism of contraction.
Optical diffraction study of muscle fibers. II. Electro-optical properties of muscle fibers.
When an electric field is applied along the fiber axis, the intensities of all observable optical diffraction lines of skeletal muscle fibers increase. This electro-optical effect was extensively studied and it was confirmed that the effect is due to the interaction between electric dipole moments of thin filaments and the applied field. From the present study on the intensity modulation due to applied field in sinusoidal and square forms, we confirmed that (1) the thin filament is a semiflexible rod, (2) the second order mode of the bending motion of thin filaments contributes to the electro-optical effect of muscle fibers at higher frequencies of a sinusodidal field or shorter durations of a square field, (3) the induced moment has no appreciable effect, and (4) the estimated value of the flexural rigidity of thin filaments strongly depends on the concentrations of free calcium ions in the myofibrillar space.
Connectin, an elastic protein of muscle. Characterization and Function.
Explore the source record for details and available documents.
New elastic protein from muscle.
Explore the source record for details and available documents.
The electric potential change of internal membrane during propagation of contraction in skinned fibre of toad skeletal muscle.
With skinned fibres prepared by removing sarcolemma in liquid paraffin from single fibres isolated from m. adductor magnus, m. sartorius or m. rectus internus major of toad (Bufo bufo japonicus), it was determined whether or not an action potential ("internal action potential", or IAP) could be detected during a propagated contraction evoked by electrical square pulses of 1 msec duration. The IAP less than 10 mV was recorded with a glass capillary microelectrode inserted into the skinned fibre during a contraction propagating along the skinned fibre. The shape of the IAP was similar to the action potential of a surface membrane of the skeletal muscle fibre, although its time course was far slower. The rate of rise of IAP was more rapid than that of the mechanical movement which was measured by the change in scattered light quantity of a gas-laser beam. When a contraction wave was propagated as far as the unskinned portion it reflected there and began to propagate backwards along the skinned portion. Whenever a contraction wave passed through the microelectrode-inserted portion, the IAP was recorded. When the propagation of a contraction wave was blocked somewhere in the skinned fibre, a potential change in reverse direction was recorded there. The phase of this potential change corresponded with the after potential of the IAP.
[Proceedings: Membrane characteristics of skeletal muscle fibers].
Explore the source record for details and available documents.
Some physiological aspects of internal membrane of skeletal muscle fibers.
Explore the source record for details and available documents.
[Present status and problems in physiological study of muscular contraction].
Explore the source record for details and available documents.
[Excitation-contraction coupling in the skeletal muscle].
Explore the source record for details and available documents.