Kawai Y, Yokoyama S, Ohhashi T
1st Department of Physiology, Shinshu University School of Medicine, Matsumoto, Japan.
Can J Physiol Pharmacol. 1991 Dec;69(12):1889-95. doi: 10.1139/y91-279.
The time course of contractile responses to alpha-adrenoceptor agonists was investigated using various arteries isolated from dogs and monkeys. The contractile response to norepinephrine was increased during the time course of the experiment in canine basilar and internal carotid arteries, whereas the response of isolated canine external carotid arteries and monkey internal carotid arteries did not change significantly. Treatment with 10(-7) M propranolol, 5 x 10(-6) M cocaine plus 10(-5) M hydrocortisone, or 5 x 10(-5) M acetylsalicylic acid did not significantly affect the time-dependent potentiation of the norepinephrine-induced contraction in canine internal carotid arteries. The time-dependent enhancement in the response to norepinephrine was also observed in the arterial preparations from which the endothelial cells were removed. The contractile response of canine internal carotid arteries to phenylephrine did not alter significantly throughout the experiments. On the other hand, the responses to clonidine and xylazine were markedly enhanced with time. Significant potentiation of the norepinephrine-induced contraction was observed in canine internal carotid arteries treated with 10(-8) M prazosin, whereas 10(-8) M yohimbine attenuated the time-dependent potentiation. These results suggest that the contractile responses of isolated canine basilar and internal carotid arteries to norepinephrine are potentiated during the course of the experiment, which is likely to be related, in part, to an enhancement in alpha 2-adrenoceptor mediated contraction.
利用从狗和猴子身上分离出的各种动脉，研究了对α-肾上腺素能受体激动剂的收缩反应的时间进程。在实验过程中，犬基底动脉和颈内动脉对去甲肾上腺素的收缩反应增强，而分离出的犬颈外动脉和猴颈内动脉的反应没有显著变化。用10（-7）M普萘洛尔、5×10（-6）M可卡因加10（-5）M氢化可的松或5×10（-5）M乙酰水杨酸处理，对犬颈内动脉中去甲肾上腺素诱导的收缩的时间依赖性增强没有显著影响。在去除内皮细胞的动脉制剂中也观察到对去甲肾上腺素反应的时间依赖性增强。在整个实验过程中，犬颈内动脉对去氧肾上腺素的收缩反应没有显著改变。另一方面，对可乐定和赛拉嗪的反应随时间显著增强。在用10（-8）M哌唑嗪处理的犬颈内动脉中观察到去甲肾上腺素诱导的收缩有显著增强，而10（-8）M育亨宾减弱了时间依赖性增强。这些结果表明，在实验过程中，分离出的犬基底动脉和颈内动脉对去甲肾上腺素的收缩反应增强，这可能部分与α2-肾上腺素能受体介导的收缩增强有关。
