腺苷对大鼠背根节神经元膜电位及动作电位的影响

EFFECT OF ADENOSINE ON RESTING AND ACTION POTENTIALS OF RAT DRG NEURONS IN VITRO

在离体灌流的大鼠背根神经节（ＤＲＧ）－脊髓标本上，用微电极进行了胞内记录。在１５７个神经元中，依神经纤维的传导速度将神经元分为Ａ类和Ｃ类，其中Ａ类７５个，Ｃ类８２个。当浴槽中滴加０．５×１０－６ｍｏｌ／Ｌ的２－氯腺苷（ＣＡＤＯ）后，６６．７％（１０／１５）的Ｃ类细胞发生了去极化；而只有３３．３％（４／１２）的Ａ类细胞发生了去极化，且其去极幅值及持续时间均小于Ｃ类细胞的效应。先加入２．５×１０－６ｍｏｌ／Ｌ的８－苯茶碱（８—ＰＴ），再给予ＣＡＤＯ，８５．７％（６／７）的Ｃ类细胞的静息电位无变化，只有１４．３％（１／７）的Ｃ类细胞出现了暂短的去极化效应。另外，给予ＣＡＤＯ后，５８．３％（７／１２）的Ｃ类细胞动作电位幅值减少，有些细胞伴有膜的去极化；但Ａ类细胞的动作电位幅度末见明显变化。结果表明：腺苷主要引起ＤＲＧ中Ｃ类细胞去极化，并减小其动作电位。

Intracellular recordings were made to investigate the effects of 2-chloroadenosine(CADO) on resting potential(RP)and action potential(AP)of 157 neurons(A cell 75 units, C cell 82 units) in isolated newborn rat dorsal root ganglion(DRG).Of 15 C cells, CADO (0.5×10~6mol/L), an adenosine receptor agonist, depolarized 10 cells with amplitude of 37.71±4.7mV (X±SE), but had no effect in the other 5. In 12 A cell examined, CADO (0.5×10~6mol/L) produced depolarization in 4 neurons with amplitude of 18.21±11.8mV. After bath application of 8-phenytheophylline, an adenosine receptor antagonist, short and transient depolarization evoked by CADO was observed in only I cell out of 7 C cells.Besides, 58.3%(7/12) C cell tested showed decrease in the amplitude of their action potentials after application of CADO.The results suggest that adenosine induces depolarization mainly in subpopulation of C DRG neurons with inhibition of action potentials.