Ramage A G, Tomlinson A
Eur J Pharmacol. 1985 Feb 26;109(2):153-60. doi: 10.1016/0014-2999(85)90416-9.
Preganglionic sympathetic nerve activity, blood pressure, heart rate and femoral arterial conductance were recorded in anaesthetised, paralysed cats. Cumulative dose (0.01-1 mg kg-1) response curves were constructed for the alpha 2 adrenoceptor antagonists yohimbine, WY 26392 and idazoxan. Low doses of these drugs caused increases in preganglionic sympathetic nerve activity, heart rate and mean blood pressure, and decreases in femoral arterial conductance. In contrast, at the highest dose, all three drugs caused falls in mean blood pressure, decreases in heart rate and no further increases in preganglionic sympathetic nerve activity. The decreases in heart rate appeared to be due to increases in vagal tone since they were reversed by atropine methonitrate. These results demonstrate that low doses of alpha 2 adrenoceptors antagonists increase central sympathetic tone and blood pressure and are consistent with the hypothesis that central alpha 2 adrenoceptors are under a tonic input which is inhibitory to central sympathetic tone.
在麻醉、麻痹的猫身上记录节前交感神经活动、血压、心率和股动脉传导。构建了α2肾上腺素能拮抗剂育亨宾、WY 26392和咪唑克生的累积剂量（0.01 - 1毫克/千克）反应曲线。这些药物的低剂量会导致节前交感神经活动、心率和平均血压升高，以及股动脉传导降低。相反，在最高剂量时，所有三种药物都会导致平均血压下降、心率降低，且节前交感神经活动不再进一步增加。心率降低似乎是由于迷走神经张力增加，因为它们可被硝酸甲基阿托品逆转。这些结果表明，低剂量的α2肾上腺素能拮抗剂会增加中枢交感神经张力和血压，这与中枢α2肾上腺素能受体受到对中枢交感神经张力起抑制作用的紧张性输入这一假设一致。
