Ryu P D, Gerber G, Murase K, Randic M
Department of Veterinary Physiology and Pharmacology, Iowa State University, Ames 50011.
Brain Res. 1988 Feb 16;441(1-2):357-61. doi: 10.1016/0006-8993(88)91414-x.
The membrane actions of calcitonin gene-related peptide (CGRP) and the effect on the Ca-dependent action potential of dorsal horn neurons have been investigated by means of an intracellular recording technique in the immature rat in vitro spinal cord slice-dorsal root ganglion preparation. Bath application of CGRP (10(-8)-10(-6) M for 1-10 min) produced a slow reversible depolarization in about one-third of the cells examined. Biphasic membrane response consisting of an initial hyperpolarization followed by a late prolonged depolarization was seen in a smaller proportion of tested cells. Both membrane responses were present, and even enhanced, when synaptic transmission and Na spikes were blocked by perfusing the slice with a TTX-containing Krebs solution. The CGRP-induced membrane changes were also present in media containing TTX and TEA. The CGRP-evoked depolarization was associated with an increase in the input resistance, and enhanced excitability in a majority of neurons tested. In addition, CGRP modified the duration of Ca-dependent action potentials of dorsal horn neurons, the most consistent change being a prolonged increase in the spike duration. Our results are consistent with a neurotransmitter or neuromodulator role for CGRP in the rat spinal dorsal horn.
利用细胞内记录技术，在体外培养的未成熟大鼠脊髓切片 - 背根神经节标本中，研究了降钙素基因相关肽（CGRP）的膜作用及其对背角神经元钙依赖性动作电位的影响。浴槽应用CGRP（10⁻⁸ - 10⁻⁶ M，持续1 - 10分钟）在约三分之一的受试细胞中产生了缓慢可逆的去极化。在较小比例的受试细胞中观察到了双相膜反应，包括初始超极化，随后是晚期延长的去极化。当用含TTX的Krebs溶液灌注切片阻断突触传递和钠峰时，两种膜反应均存在，甚至增强。CGRP诱导的膜变化在含有TTX和TEA的培养基中也存在。CGRP诱发的去极化与输入电阻增加以及大多数受试神经元的兴奋性增强有关。此外，CGRP改变了背角神经元钙依赖性动作电位的持续时间，最一致的变化是动作电位持续时间的延长增加。我们的结果与CGRP在大鼠脊髓背角中作为神经递质或神经调质的作用一致。
