Electrophysiological and relevant morphological properties of neurons in toad dorsal root ganglion

Abstract

Intracellular recordings were performed on isolated preparations of toad dorsal root ganglion (DRG). Of the 87 neurons examined, 83 were of type A cells and 4 of type C cells. The conduction velocity (CV) of type A cells ranged from 2.55 to 35.19 m/s with a mean of 11.18±0.78 m/s (x ± s x), while that of type C cells ranged from 1.34 to 2.43 m/s with a mean of 2.11±0.22 m/s (x ± s x). On the basis of tne characteristics of Ap configuration, these 87 cells can be classified into three groups: H neuron (24/87); F neuron (50/87) and F-H neuron (13/87). The Sizes of DRG cells were examined by measuring of HRP labelled cells in part of the experiment. By comparing the size of F and H cell with tneir CV, we proposed a revised view which is against the public opinion concerning the relation between tne size and CV of DRG cells.

Keywords

dorsal root ganglion / intracellular recordings / HRP labelling / toad

References

[1] WillisW D, CoggeshallR E. Sensory Mechanisms of the Spinal Cord, 1978Wuhan and LondonPlenum Press46-51

[2] HarperA A, LawsonS N. Conduction velocity is related to morphological cell type in rat dorsal root ganglion neurons. J Physiol, 1985, 359: 31-46

[3] LiebermanA R. LandonD.N.. Sensory ganglia. The Peripheral Nerve, 1976LondonChapman and Hall188-278

[4] SommerE W, KazimierezakJ, DrozB. Neuronal subpopulations in the dorsal root ganglion of the mouse as characterized by combination of ultrastructural and cytochemical features. Brain Res, 1985, 346: 310-326

[5] MoritaK, KatayamaY. Bullfrog dorsal root ganglion cells having tetrodotoxin-resistant spikes are endowed wih nicotinic receptors. J Neurophysiol, 1989, 62: 657-664

[6] YoshidaS, MatsudaY, SamejimaA. Tetradotox in-resistant sodium and calcium components of action potentials in dorsal root ganglion cells of the adult mouse. J Neurophysiol, 1978, 41: 1096-1106

[7] YoshidaS, MatsudaY. Studies on sensory neurons of the mouse with intracellular-recording and horseradish peroxidase-injection techniques. J Neurophysiol, 1979, 42: 1134-1145

[8] MoralesA, IvorraI, GallegoR. Membrane properties of glossopharyngeal sensory neurons in the petrosal ganglion of the cat. Brain Res, 1987, 401: 340-346

[9] ItoM. The electrical activity of spinal ganglion cells investigated with intracellular microelectrodes. Jap J Physiol, 1957, 7: 297-323

[10] ItoM, SaigaM. The mode of impulse conduction through the spinal ganglion. Jap J Physiol, 1959, 9: 33-42

[11] 1988;40:240–249

[12] 1989;18:173–176

[13] 1988;5:195–196

[14] GasserH S. Unmedullated fibres originating in dorsal root ganglia. J Gen Physiol, 1950, 33: 651-690

[15] 1978:1403

[16] 1985; 16:67–70

[17] ErlangerJ, GasserHS. Electrical Signs of Nervous Activity, 1937PhiladelphiaUniversity of Pennsylvania Press

[18] HolzG G, ShefnerS A, AndersonE G. Serotonin depolarizes type A and C Primary afferents, an intracellularstudy in bullfrog dorsal root ganglion. Brain Res, 1985, 327: 71-79

[19] HoheiselU, MenseS. Observations on ihe morphology of axons and somata of slowly conducting dorsal root ganglion cells in the cat. Brain Res, 1987, 423: 269-278