引起牛蛙腹根电位的传入纤维类别分析

实验用牛蛙,以坐骨神经干复合动作电位作为监测纤维类别的指标,对引起牛蛙腹根电位(VRP)的传入纤维类别进行了分析。实验中可见,当刺激强度为0.054±0.003使时,随动作电位α波的出现,在腹根可记录到前人所报道的短潜伏期的VRP,即A类纤维引起的VRP(A—VRP)。当刺激强度增加到70T左右,在A—VRP之后出现一长潜伏期的VRP。该波与A—VRP的极性一致;在300T达最大幅度。用普鲁卡因阻滞、三角波刺激、远侧与近侧刺激对比的方法,证明了这一长潜伏期的VIIP是由C类传入诱发的,命名为C—VRP。实验结果证明:牛蛙坐骨神经的C类纤维也可诱发VRP。C—VRP似可作为一个“痛”反应指标。

ANALYSIS OF THE GROUPS OF AFFERANT FIBRES EVOKING VENTRAL ROOT POTENTIALS IN BULLFROGS

The experiments were carried out in bullfoogs. The compound action potentials of the sciatic nerve were recorded and the AP conduction velosity was calculated as an identification index of afferent fibre groups, when the stimulation intensity was 0.054±0.003V, short latency VRPs (AVRP) in ventral root appeared, which were connection with the excitation of A group fibres (including A_α. A_β. A_δ fibres). When stimulation intensity was strong enough (about 70T), to activite the C fibres of the nerve, the A-VRPs were followed by a late negative wave (C-VRP) which was the same with the A-VRPs in the polarity and reached the maximum at the intensity of 300T, The C-VRP being due to activation of C fibres was further demonstrated by the following experiments: (1) Comparing distal stimulus with proximal stimulus, (2) Triangularly shaped stimulus, (3) Procane block. The results suggest that not only myelinated fibres but also nonmyclinated fibres can evoke VRPs in bullfrogs, and the C-VRP mighrt be employed as a pain reaction index.