颈动脉注射腺苷对去缓冲神经大鼠延髓腹外侧头端区神经元放电的影响(英文)

EFFECT OF INTRACAROTID INJECTION OF ADENOSINE ON THE ACTIVITY OF RVLM NEURONS IN BARODENERVATED RATS

在28只切断双侧缓冲神经的Sprague－Dawley大鼠，应用细胞外记录方法，观察了72个自发放电单位中颈动脉注射腺苷对延髓腹外侧头端（RVLM）区神经元自发放电活动的影响。所得结果如下：（1）颈动脉注射腺苷（25μg/kg），31个单位的放电频率由23．5±3．0下降至（16．5±2．6）spikes／s（P＜0．001），血压和心率无明显变化（P＞0．05）；（2）在24个单位中，应用非选择性腺苷受体拮抗剂8-苯茶碱（8-phenyltheophylline，15μg/kg）和选择性腺苷A1受体持抗剂8-环戊-1，3-二丙基黄嘌呤（8－cyclopentyl-1，3－dipropylxanthine，50μg/kg）均可完全阻断腺苷的抑制效应；（3）在应用ATP敏感性钾通道阻断剂格列苯脲（500μg/kg）的12个单位中，腺苷的上述效应亦被消除。以上结果提示，腺苷对RVLM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。

To observe the effect of intracarotid administraation of adenosine on neurons in the rostral ventrolateral medulla (RVLM) region, 72 spontaneous active units were extracellulary recorded from 28 Sprague-Dawley rats with sino-aortic denervation. The results obtained are as follows: (1) intracarotidadministration of Ado (25 μg/kg) reduced the discharge rate from (23 .5 ± 3.0) to (16.5± 2.6) spikes/s (P< 0.001) in 31 out of 36 RVLM neurons, while the blood pressure and heart rate had no significant change (P > 0.05); (2) 8-phenyltheohylline (8-PT, 15 μg/kg), a nonselective adenosine receptor antagonist, and 8-cyclopentyl-1,3-dipropylxanthinee (DPCP, 50 μg/kg), a selective A1 adenosine receptor antagonist,completely blocked the inhibitory effects of Ado in 24 units; and (3) in 12 units, glibenclamide (500) μg/kg), a blocker of ATP-sensitive potassium channel, abolished the effect of Ado. These results indicate that Ado can indue an inhibition of spontaneous electrical activity of RVLM neurons an effect which is mediated by adenosine A1-receptor with the involvement of AFP-sensitive potassium channels.