Cruzblanca H, Alvarez-Leefmans F J
Departamento de Neurobiología, Instituto Mexicano de Psiquiatría, México, D.F.
Neuroscience. 1989;33(1):193-201. doi: 10.1016/0306-4522(89)90321-7.
The effect of temperature on electrical interactions between antidromically stimulated motoneurons and dorsal root afferents was studied in the isolated and hemisected spinal cord of the frog, superfused with Ringer in which Ca2+ was equimolarly replaced by Co2+ or Mn2+ to suppress chemical synaptic transmission. Suction electrodes were used for stimulating and/or recording from dorsal and ventral roots from segments IX or X. Intrafibre recordings from sensory fibres were made at their point of entry into the spinal cord. Supramaximal ventral root stimuli elicited two distinct responses in the segmental dorsal root. First a brief short-latency depolarizing potential. Second, at temperatures below 11 degrees C, a second depolarizing root potential appeared following the short-latency depolarizing potential-I. Amplitude and duration of short-latency depolarizing potential-II reversibly increased as the bath temperature was decreased, reaching a maximum at 3 degrees C. Between 8 and 3 degrees C, short-latency depolarizing potential-II increased in amplitude by 20%/degrees C. In contrast short-latency depolarizing potential-I did not show substantial changes with temperature. The short-latency depolarizing potential-II, unlike short-latency depolarizing potential-I showed stepped fluctuations in amplitude, and appeared to be composed of unitary events. Intrafibre records revealed that the unitary events corresponded to action potentials on individual dorsal root fibres. Double shocks applied to the ventral root, at constant bath temperatures (below 11 degrees C), revealed facilitation of the short-latency depolarizing potential-II, which was maximal between 50 and 80 ms and lasted about 200 ms. Neither the antidromic motoneurone field potential nor the short-latency depolarizing potential-I were facilitated.(ABSTRACT TRUNCATED AT 250 WORDS)
在青蛙的离体半切脊髓中研究了温度对抗向刺激运动神经元与背根传入纤维之间电相互作用的影响，该脊髓用林格液灌流，其中Ca2+被等摩尔的Co2+或Mn2+取代以抑制化学突触传递。使用吸力电极刺激和/或记录IX或X节段的背根和腹根。在感觉纤维进入脊髓的部位进行纤维内记录。腹根的超强刺激在节段背根中引发了两种不同的反应。首先是一个短暂的短潜伏期去极化电位。其次，在温度低于11摄氏度时，在短潜伏期去极化电位-I之后出现第二个去极化根电位。短潜伏期去极化电位-II的幅度和持续时间随着浴温降低而可逆性增加，在3摄氏度时达到最大值。在8至3摄氏度之间，短潜伏期去极化电位-II的幅度以每摄氏度20%的速度增加。相比之下，短潜伏期去极化电位-I没有随温度发生实质性变化。与短潜伏期去极化电位-I不同，短潜伏期去极化电位-II的幅度呈现阶梯状波动，并且似乎由单个事件组成。纤维内记录显示，单个事件对应于单个背根纤维上的动作电位。在恒定浴温（低于11摄氏度）下对腹根施加双次刺激，显示短潜伏期去极化电位-II出现易化，在50至80毫秒之间最大，持续约200毫秒。逆向运动神经元场电位和短潜伏期去极化电位-I均未出现易化。（摘要截于250字）
