Burgstahler R, Grafe P
Department of Physiology, University of Munich, Germany.
Neuroreport. 2001 Mar 26;12(4):679-82. doi: 10.1097/00001756-200103260-00012.
The effects of diadenosine pentaphosphate (Ap5A), diadenosine tetraphosphate (Ap4A), alpha,beta-methyleneATP (alpha,beta-meATP), and ATP were studied on the excitability of unmyelinated axons in isolated rat vagus nerve by means of a computerized threshold tracking technique. All purinergic compounds produced an increase in excitability, however, only the effects of alpha,beta-meATP and of Ap5A were strongly reduced by 2'- (or 3') -O-(2,4,6-trinitrophenyl)-ATP (TNP-ATP), a selective blocker for P2X1, P2X3, and heteromeric P2X2/3 receptors. The rank order of potency for TNP-ATP-sensitive excitation was determined as follows (30 microM each): alpha,beta-meATP >Ap5A >> Ap4A = ATP. These data suggest that Ap5A might be an important naturally occurring agonist for P2X receptors at the axonal membrane of unmyelinated, including nociceptive, nerve fibres.
运用计算机化阈值跟踪技术，研究了五磷酸二腺苷（Ap5A）、四磷酸二腺苷（Ap4A）、α,β-亚甲基三磷酸腺苷（α,β-meATP）和三磷酸腺苷（ATP）对离体大鼠迷走神经无髓鞘轴突兴奋性的影响。所有嘌呤能化合物均使兴奋性增加，然而，只有α,β-meATP和Ap5A的作用被2'-（或3'）-O-（2,4,6-三硝基苯基）-三磷酸腺苷（TNP-ATP）强烈减弱，TNP-ATP是P2X1、P2X3和异聚体P2X2/3受体的选择性阻断剂。TNP-ATP敏感兴奋的效力排序如下（各为30微摩尔）：α,β-meATP＞Ap5A＞＞Ap4A = ATP。这些数据表明，Ap5A可能是无髓鞘神经纤维（包括伤害性神经纤维）轴突膜上P2X受体的一种重要的天然激动剂。
