Biomedical subjects

Y Miyata

Publications and source records attributed to Y Miyata.

At least 397 records · Page 22Linked to original sources

PubMed1974

Differential reaction of fast and slow alpha-motoneurones to axotomy.

1. The properties of medial gastrocnemius (m.g., fast alpha) and soleus (sol., slow alpha) motoneurones of the cat were examined with intracellular electrodes 8-119 days after section of the muscle nerves.2. The axonal conduction velocity was significantly decreased in both m.g. and sol. motoneurones after chronic section of the muscle nerves.3. The amplitude of overshoot of action potentials was significantly increased in both m.g. and sol. motoneurones following section of the muscle nerves.4. No significant changes in the resting membrane potential or the input resistance were observed for sol. motoneurones, whereas m.g. motoneurones showed a slight decrease in the resting potential and a slight increase in the input resistance.5. The duration of after-hyperpolarization was significantly decreased in sol. motoneurones, whereas that in m.g. motoneurones remained virtually unchanged or increased slightly following section of the muscle nerves.6. The changes described above were not seen in the preparations examined 29-46 days after section of the lumbosacral dorsal roots, suggesting that alterations in the motoneurone properties observed after section of the muscle nerves resulted from axotomy of the motoneurones rather than from sensory deprivation.7. The differences in electrophysiological properties between m.g. and sol. motoneurones were less prominent in axotomized animals than in control, unoperated cats.8. It is concluded that fast (m.g.) and slow (sol.) alpha-motoneurones have qualitatively different properties. A possible ;dedifferentiation' of fast and slow alpha-motoneurones by axotomy is discussed.

Action Potentials↗

PubMed1974

Properties of fast and slow alpha motoneurones following motor reinnervation.

1. The properties of medial gastrocnemius (fast alpha) and soleus (slow alpha) motoneurones of the cat were examined with intracellular electrodes 33-154 days after self- or cross-union of the muscle nerves.2. The original properties of fast and slow alpha motoneurones measured in terms of the axonal conduction velocity, the duration of after-hyperpolarization and the overshoot amplitude were restored at least in part after self-union of the muscle nerves.3. Slow alpha motoneurones recovered their original properties whether the muscle nerve was united to the original, slow red muscle or to the fast pale muscle. In two animals, some of the fast muscle fibres seemed to be doubly innervated by both fast and slow alpha motoneurones.4. The degree of restoration of the original motoneurone properties was closely related to the degree of motor reinnervation of the muscle.5. At a given stage of motor reinnervation, the degree of recovery of the motoneurone properties was approximately the same regardless of the presence or absence of functional motor connexions of the motoneurone under study.6. When the dorsal root ganglia were removed immediately before self-union of the muscle nerves, recovery of the conduction velocity of motoneurones was impeded without significant effect upon the process of motor reinnervation or upon recovery of the overshoot amplitude and the duration of after-hyperpolarization.7. It is concluded that the ;dedifferentiated' properties of fast and slow alpha motoneurones after nerve section may be ;redifferentiated' following motor reinnervation to any muscle. The possible signal for restoration of the motoneurone properties is discussed.

Action Potentials↗

PubMed1974