Age-related changes in adrenergic vasoconstrictor responses of the rat hindlimb.
Age-related changes in adrenergic vasoconstrictor responses of the rat hindlimb.
复制标题
大鼠后肢肾上腺素能血管收缩反应的年龄相关变化。
DOI：
10.1152/ajpheart.1987.253.6.h1566
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发表时间：
1987
期刊：
影响因子：
--
通讯作者：
Duckles,SP
中科院分区：
文献类型：
--
作者：
Handa,RK;Duckles,SP
用戊巴比妥钠麻醉的雄性Fischer 344大鼠，在6、12、20和24个月龄的后肢恒流灌流血管肾上腺素能反应。在20和24个月龄的大鼠中，腰交感神经刺激的后肢灌流压的增加明显小于年轻动物，而动脉内注射去甲肾上腺素、L-苯肾上腺素和甲氧胺的血管收缩反应仅在24个月龄的动物中降低。因此，后肢神经源性血管收缩在20个月龄时减少，而在24个月龄时有更广泛的肾上腺素能反应丧失。在β-肾上腺素能受体拮抗剂心得安的存在下，当比较12个月和20个月龄的动物时，对外源性去甲肾上腺素的血管收缩反应没有差别。此外，在普萘洛尔存在的情况下，12个月龄和20个月龄大鼠的后肢灌注压的神经介导的升高也没有差别。用可卡因阻断神经元去甲肾上腺素摄取，在老年大鼠对神经刺激和外源性去甲肾上腺素的血管收缩反应产生更大的增强。因此，20个月龄大鼠神经介导的血管收缩减少可能是由于神经元激活β-肾上腺素受体和增强神经元对去甲肾上腺素的再摄取。
Vascular adrenergic responses were examined in the hindlimb perfused with blood at constant flow using pentobarbital-anesthetized male Fischer 344 rats aged 6, 12, 20, and 24 mo. The increase in hindlimb perfusion pressure to lumbar sympathetic nerve stimulation was significantly smaller in 20- and 24-mo-old rats than in younger animals, whereas vasoconstrictor responses to intraarterial administration of norepinephrine, L-phenylephrine, and methoxamine were reduced only in the 24-mo-old animals. Thus neurogenic vasoconstriction in the hindlimb is reduced at 20 mo of age, whereas there is a more generalized postjunctional loss of adrenergic responsiveness at 24 mo. In the presence of the beta-adrenoceptor antagonist, propranolol, vasoconstrictor responses to exogenous norepinephrine did not differ when 12- and 20-mo-old animals were compared. Furthermore, in the presence of propranolol the nerve-mediated rise in hindlimb perfusion pressure also did not differ in 12- and 20-mo-old rats. Blockade of neuronal norepinephrine uptake with cocaine produced a greater potentiation of vasoconstrictor responses to both nerve stimulation and exogenous norepinephrine in the older rats. Therefore, the reduced nerve-mediated vasoconstriction in 20-mo-old rats may be due to neuronal activation of beta-adrenoceptors as well as enhanced neuronal norepinephrine reuptake.