Wilffert B, Gouw M A, De Jonge A, Timmermans P B, van Zwieten P A
J Pharmacol Exp Ther. 1982 Oct;223(1):219-23.
In the pithed normotensive rat the adrenoceptors involved in the hypertensive and tachycardic effects of the indirectly acting sympathomimetic agent tyramine and of electrical stimulation of the spinal cord (TH5-L4 or C7-Th1) were analyzed. The tools used for the identification of the adrenoceptors were the selective alpha-1 adrenoceptor blocking drug prazosin, the selective alpha-2 adrenoceptor antagonist rauwolscine, the beta-1 blocker atenolol and the selective beta-2 adrenoceptor blocking agent ICI 118,551. The participation of vascular alpha-2 adrenoceptors in the pressor response of tyramine was shown. The increase in blood pressure induced by electrical stimulation of the spinal cord (TH5-L4) was used to demonstrate that alpha-2 adrenoceptors were activated via ganglionic muscarinic receptors. The tachycardia evoked by electrical stimulation of the spinal cord (C7-Th1) was not influenced by beta-2 adrenoceptor blockade. It was enhanced, however, by the alpha-2 adrenoceptor antagonist rauwolscine. It is hypothesized that activation of ganglionic nicotinic receptors leads to stimulation of the nearest varicosities interfering with alpha-1 adrenoceptors. However, activation of ganglionic muscarinic receptors may lead to an additional release of neurotransmitter in the more distant varicosities endowed with alpha-2 or beta-2 adrenoceptors.
在脊髓横断的正常血压大鼠中，分析了间接作用拟交感神经药酪胺以及脊髓（胸5 -腰4或颈7 -胸1）电刺激所产生的升压和心动过速效应中涉及的肾上腺素能受体。用于鉴定肾上腺素能受体的工具包括选择性α1肾上腺素能受体阻断药哌唑嗪、选择性α2肾上腺素能受体拮抗剂育亨宾、β1受体阻滞剂阿替洛尔以及选择性β2肾上腺素能受体阻断剂ICI 118,551。结果显示血管α2肾上腺素能受体参与了酪胺的升压反应。利用脊髓（胸5 -腰4）电刺激诱导的血压升高来证明α2肾上腺素能受体是通过神经节毒蕈碱受体被激活的。脊髓（颈7 -胸1）电刺激诱发的心动过速不受β2肾上腺素能受体阻断的影响。然而，α2肾上腺素能受体拮抗剂育亨宾可增强该心动过速。据推测，神经节烟碱受体的激活会导致最邻近的曲张体受到刺激，从而干扰α1肾上腺素能受体。然而，神经节毒蕈碱受体的激活可能会导致在具有α2或β2肾上腺素能受体的更远端曲张体中额外释放神经递质。
