Hyland L, Warnock P, Docherty J R
Naunyn Schmiedebergs Arch Pharmacol. 1987 Jan;335(1):50-3. doi: 10.1007/BF00165035.
We have examined the responsiveness of alpha- and beta-adrenoceptors in aortae from 1.5, 3, 6 and 24 month old rats. The isometric contraction to phenylephrine was antagonised competitively by prazosin with a pA2 value of 9.45, suggesting that the receptor is an alpha 1-adrenoceptor. The potency of phenylephrine was significantly reduced in 24 months old as compared with all younger rats combined. The maximum contraction to phenylephrine was unaltered in 24 month old rats. The maximum contraction to potassium chloride was significantly less than that to phenylephrine only in 1.5 months old rats. In tissues contracted by potassium chloride, isoprenaline produced a marked relaxation in 1.5 months old animals, but there was a progressive loss with increasing age of the beta-adrenoceptor-mediated relaxation which was markedly reduced by 6 months and abolished in 24 months old. It is concluded that, in the rat aorta, there is a decrease in alpha 1-adrenoceptor responsiveness in senescence, and a loss of beta-adrenoceptor-mediated responses in maturation.
我们研究了1.5、3、6和24月龄大鼠主动脉中α和β肾上腺素能受体的反应性。去氧肾上腺素引起的等长收缩可被哌唑嗪竞争性拮抗，pA2值为9.45，提示该受体为α1肾上腺素能受体。与所有较年轻大鼠的总和相比，24月龄大鼠去氧肾上腺素的效力显著降低。24月龄大鼠对去氧肾上腺素的最大收缩未改变。仅在1.5月龄大鼠中，氯化钾引起的最大收缩显著小于去氧肾上腺素引起的最大收缩。在由氯化钾收缩的组织中，异丙肾上腺素在1.5月龄动物中产生明显的舒张作用，但随着年龄增长，β肾上腺素能受体介导的舒张作用逐渐丧失，6月龄时明显减弱，24月龄时消失。结论是，在大鼠主动脉中，衰老过程中α1肾上腺素能受体反应性降低，成熟过程中β肾上腺素能受体介导的反应丧失。
