Docherty J R, Hyland L
Eur J Pharmacol. 1986 Jul 15;126(1-2):75-80. doi: 10.1016/0014-2999(86)90740-5.
The effects of ageing on vascular alpha 1- and alpha 2-adrenoceptors were examined using anaesthetised and pithed young (3-7 months) and old (21-24 months) Sprague-Dawley rats. In pithed animals, the pressor and cardioinhibitory effects of the alpha 2-adrenoceptor agonist xylazine were significantly reduced in old animals (8- and 6-fold shift), but the pressor effects of the alpha 1-adrenoceptor agonist amidephrine were not significantly altered by ageing. In anaesthetised rats, the pressor response to the mixed alpha-adrenoceptor agonist noradrenaline (NA) was not significantly altered, and the pressor potency of the alpha 1-adrenoceptor agonist amidephrine was only slightly reduced (1.7-fold shift) in old animals. In the presence of cocaine (1 mg kg-1) the pressor potency of NA was markedly reduced (13-fold shift) in old animals. In the presence of prazosin (1 mg kg-1) to eliminate alpha 1-adrenoceptor-mediated responses, the pressor potency of NA was markedly reduced in old as animals as compared to young animals (16-fold shift). The neuronal uptake blocker cocaine (1 mg kg-1) significantly potentiated the pressor response to NA only in young. In summary, we have found a reduced alpha 2-adrenoceptor-mediated pressor and cardioinhibitory responsiveness and a reduced neuronal uptake of NA in old animals with little change in alpha 1-adrenoceptor-mediated vascular responsiveness.
利用麻醉和毁髓的年轻（3 - 7个月）及老年（21 - 24个月）的斯普拉格-道利大鼠，研究衰老对血管α1和α2肾上腺素能受体的影响。在毁髓动物中，α2肾上腺素能受体激动剂赛拉嗪的升压和心脏抑制作用在老年动物中显著降低（8倍和6倍的变化），但α1肾上腺素能受体激动剂美速胺的升压作用未因衰老而显著改变。在麻醉大鼠中，对混合α肾上腺素能受体激动剂去甲肾上腺素（NA）的升压反应未显著改变，α1肾上腺素能受体激动剂美速胺的升压效力在老年动物中仅略有降低（1.7倍的变化）。在存在可卡因（1 mg/kg）的情况下，老年动物中NA的升压效力显著降低（13倍的变化）。在存在哌唑嗪（1 mg/kg）以消除α1肾上腺素能受体介导的反应时，与年轻动物相比，老年动物中NA的升压效力显著降低（16倍的变化）。神经元摄取阻断剂可卡因（1 mg/kg）仅在年轻动物中显著增强了对NA的升压反应。总之，我们发现老年动物中α2肾上腺素能受体介导的升压和心脏抑制反应性降低，NA的神经元摄取减少，而α1肾上腺素能受体介导的血管反应性变化不大。
