Tschöpl M, Harms L, Nörenberg W, Illes P
Department of Pharmacology, University of Freiburg, Germany.
Eur J Pharmacol. 1992 Mar 17;213(1):71-7. doi: 10.1016/0014-2999(92)90234-u.
Pontine slices of the rat brain were used for extracellular recording of the frequency of spontaneous action potentials of locus coeruleus (LC) neurones. In the absence of 8-cyclopentyl-1,3-dipropylxanthine (DPCPX), alpha,beta-methyleneadenosine 5'-triphosphate (alpha,beta-meATP; 0.3-30 mumol/l) and 2-methylthio ATP (0.3-100 mumol/l), but not ATP (1-100 mumol/l) increased the firing rate. In the presence of DPCPX 0.1 mumol/l, all three purinoceptor agonists were active, the potency order being alpha,beta-meATP greater than 2-methylthio ATP = ATP. Preincubation of the slices with tetrodotoxin (TTX) 0.5 mumol/l decreased the spike discharge but did not alter the percent facilitatory effect of alpha,beta-meATP 30 mumol/l. There was no desensitization to alpha,beta-meATP 10 mumol/l on repeated or continuous application. Suramin 100 mumol/l selectively depressed the effect of alpha,beta-meATP 30 mumol/l without interfering with the effect of equiactive concentrations (10-100 mumol/l) of glutamic acid. The concentration-response curve of alpha,beta-meATP was shifted in a parallel manner to the right by suramin 10 mumol/l. While DPCPX 0.1 mumol/l facilitated firing, suramin 100 mumol/l did not change it. In conclusion, LC neurones may possess P2-purinoceptors of an unidentified type, which share some P2x characteristics.
采用大鼠脑桥切片进行细胞外记录蓝斑（LC）神经元的自发放电动作电位频率。在不存在8-环戊基-1,3-二丙基黄嘌呤（DPCPX）的情况下，α,β-亚甲基腺苷5'-三磷酸（α,β-meATP；0.3 - 30 μmol/L）和2-甲硫基ATP（0.3 - 100 μmol/L）可增加放电频率，但ATP（1 - 100 μmol/L）无此作用。在存在0.1 μmol/L DPCPX的情况下，所有三种嘌呤受体激动剂均有活性，其效力顺序为α,β-meATP＞2-甲硫基ATP = ATP。用0.5 μmol/L河豚毒素（TTX）预孵育切片可降低动作电位发放，但不改变30 μmol/L α,β-meATP的促发效应百分比。重复或持续应用10 μmol/L α,β-meATP不会产生脱敏现象。100 μmol/L苏拉明选择性抑制30 μmol/L α,β-meATP的作用，而不干扰等活性浓度（10 - 100 μmol/L）谷氨酸的作用。10 μmol/L苏拉明使α,β-meATP的浓度 - 反应曲线平行右移。虽然0.1 μmol/L DPCPX促进放电，但100 μmol/L苏拉明对其无影响。总之，LC神经元可能具有一种未明确类型的P2嘌呤受体，其具有一些P2x特性。
