Tsai H, Buchholz J, Duckles S P
Department of Pharmacology, College of Medicine, University of California, Irvine 92717.
Eur J Pharmacol. 1993 Jun 24;237(2-3):311-6. doi: 10.1016/0014-2999(93)90283-n.
To investigate the impact of age on function of vascular postjunctional alpha 2-adrenoceptors in tail arteries of F-344 rats aged 6 and 20 months, vasoconstrictor responses of isolated ring segments were studied. In both 6 and 20 months old animals, norepinephrine concentration response curves were significantly shifted to the right in the presence of the alpha 2-adrenoceptor antagonists idazoxan (300 nM) or rauwolscine (50 nM). Furthermore, in both age groups alpha 2-adrenoceptor agonists UK14304 (300 nM) or BHT920 (25 nM) produced significant enhancements in the vasoconstrictor response to the selective alpha 1-adrenoceptor agonist, methoxamine. Concentration response curves for norepinephrine and methoxamine were not different with age. These data verify the existence of postjunctional alpha 2-adrenoceptors and demonstrate that the function of these receptors does not change with age. This supports the proposition that overall vascular adrenergic function in blood vessels is maintained with advancing age.
为研究年龄对6月龄和20月龄F-344大鼠尾动脉血管后接头α₂-肾上腺素能受体功能的影响，对分离的动脉环段的血管收缩反应进行了研究。在6月龄和20月龄的动物中，在α₂-肾上腺素能受体拮抗剂咪唑克生（300 nM）或育亨宾（50 nM）存在的情况下，去甲肾上腺素浓度反应曲线均显著右移。此外，在两个年龄组中，α₂-肾上腺素能受体激动剂UK14304（300 nM）或BHT920（25 nM）对选择性α₁-肾上腺素能受体激动剂甲氧明的血管收缩反应均有显著增强。去甲肾上腺素和甲氧明的浓度反应曲线不随年龄变化。这些数据证实了后接头α₂-肾上腺素能受体的存在，并表明这些受体的功能不随年龄变化。这支持了随着年龄增长血管整体肾上腺素能功能得以维持的观点。
