颈动脉内注射腺苷对去缓冲神经大鼠最后区神经元放电的影响

在45只切断双侧缓冲神经的SpragueDawley大鼠,应用细胞外记录方法,观察了颈动脉内注射腺苷对76个最后区(AP)神经元自发放电活动的影响。所得结果如下:(1)在记录到的42个自发放电单位中,颈动脉内注射腺苷(25μg/kg)引起其中29个单位的放电频率由626±075下降至474±076spikes/s(P<001),6个单位放电频率由413±077增加至472±083spikes/s(P<005),另外7个单位放电频率无明显变化,而血压和心率在实验中无变化;(2)在应用非选择性腺苷受体拮抗剂8苯茶碱(8phenyltheophylline,15μg/kg)的10个单位,腺苷对放电的抑制效应可被完全阻断;(3)应用选择性腺苷A1受体拮抗剂8环戊1,3二丙基黄嘌呤(8cyclopentyl1,3dipropylxanthine,50μg/kg)亦可有效地阻断腺苷对12个单位的抑制效应;(4)应用ATP敏感性钾通道阻断剂格列苯脲(500μg/kg)的12个单位,腺苷的上述效应也被消除。以上结果提示,腺苷对AP区神经元自发放电有抑制作用,而此作用与A1受体介导的ATP敏感性钾通道开放有关。

EFFECT OF INTRACAROTID ADMINISTRATION OF ADENOSINE ON THE ACTIVITY OF AREA POSTREMA NEURONS IN BARODENERVATED RATS

To observe the effect of intracarotid administration of adenosine on the electrical activity of area postrema (AP) neurons, 76 spontaneous active units were recorded from 45 sino-aortic denervated Sprague-Dawley rats using extracellular recording technique. The results obtained are as follows. (1) Following intracarotid administration of adenosine (Ado, 25 μg/kg), the discharge rate of 29 out of 42 units decreased markedly from 6.26±0.75 to 4.74±0.76 spikes/s (P<0.01), whereas that of 6 units increased from 4.13±0.77 to 4.72±0.83 spikes/s (P<0.05), and the other 7 showed no response. Blood pressure (BP) and heart rate (HR) were unaltered throughout the experiment. (2) 8-phenyltheophylline (8-PT, 15 μg/kg), a nonselective adenosine receptor antagonist, completely blocked the inhibitory effect of Ado in 10 units. (3) Selective A1 adenosine receptor antagonist, 8-cyclopentyl-1,3-dipropylxanthine (DPCPX, 50 μg/kg), blocked the effect of Ado in 12 units to a remarkable extent. (4) Glibenclamide (500 μg/kg), a blocker of ATP-sensitive potassium channel, abolished the effect of Ado in 12 units. The above results indicate that Ado can inhibit spontaneous electrical activity of AP neurons, which is mediated by adenosine A1-receptor with the involvement of ATP-sensitive potassium channels.