ABSTRACT
The changes of rheobase(Rh), chronaxie(Chr), standard electrical quantity(a) and mtensity-duration curve(i. t. c) were studied for understanding the effect of aging on the excitability of sciatic and caudal nerves in Wistar rats of different age. The results show that before grown-up excitability of the peripheral nerves increases progressively with age, after that it tends to decrease. Chronaxie as an index can not reflect the change of excitability of the peripheral nerves correctly.
ABSTRACT
This paper reports the effect of sodium selenite on dorsal root potentials(DR-DRP; VR-DRP)in the isolated toad spinal cord. The results indicate that selenite has a double phase effect or dorsal root potentials, that is, increasing the amplitude first, and then decreasing it. Using sucrose gap technique, we have proved that selenite has a dcoplarization effect on the dorsal roots. Further experiments indicate that spontaneous dorsal root potentials induced by selenite are attributed to its actions on the interneurons activities of the spinal cord. In addition, the mechanism of selenite's effects was discussed.
ABSTRACT
The effects of sodium selenite on ventral root reflexs in the isolated spinal cord of the toad were investigated. It was found that the effects of selenite on ventral root reflexs were excited first and then inhibited gradually. Using sucrose gap technique, we have found that selenite produced a significant depolarization on the rentral roots. Mg~(2+)ion markedly reduced this effect, which indicated that selenite had an importment action on interneurons activities of the spinal cord. Sodium selenite could antagonized the post-tetanus hyperpolarization of the ventral roots, which gave another evidenoe for proving its depolarization. The data described above suggest that the actions of sodium selenite on toad spinal cord are exciting first and then inhibiting gradually.