Ayajiki K, Toda N
Department of Pharmacology, Shiga University of Medical Sciences, Ohtsu, Japan.
Eur J Pharmacol. 1990 Dec 4;191(3):417-25. doi: 10.1016/0014-2999(90)94176-x.
Responsiveness to norepinephrine and related agents was compared in isolated bovine anterior cerebral (ACA). middle cerebral (MCA), intracranial internal carotid (ICA), posterior communicating (PCOM), posterior cerebral (PCA) and basilar arteries (BA). Norepinephrine contracted the strips from ACA, MCA and ICA, but relaxed those from PCOM, PCA and BA. In the presence of propranolol, the amine-induced contractions tended to be potentiated in ACA, MCA and ICA, and the relaxations in PCOM, PCA and BA were reversed to contractions. The maximum contractions induced by norepinephrine in ICA and ACA treated with propranolol were significantly greater than those in PCA and BA, but the EC50 values did not differ among arteries. In ACA and MCA, the contractions induced by phenylephrine were greater than those induced by clonidine. The contractions induced by norepinephrine and phenylephrine were attenuated by prazosin but not influenced by yohimbine in ACA and MCA treated with propranolol. These findings indicate that the responses to norepinephrine evidently differ in bovine cerebral arteries of rostral (ACA, MCA and ICA) and caudal regions (PCOM, PCA and BA), possibly due to different functioning of alpha/beta receptors. The amine-induced contraction predominantly seen in the rostral arteries appears to be associated with activation of the alpha 1 adrenoceptor subtype.
在离体牛大脑前动脉（ACA）、大脑中动脉（MCA）、颅内颈内动脉（ICA）、后交通动脉（PCOM）、大脑后动脉（PCA）和基底动脉（BA）中比较了对去甲肾上腺素及相关药物的反应性。去甲肾上腺素使ACA、MCA和ICA的血管条收缩，但使PCOM、PCA和BA的血管条舒张。在普萘洛尔存在的情况下，胺诱导的ACA、MCA和ICA收缩倾向于增强，而PCOM、PCA和BA的舒张则逆转至收缩。用普萘洛尔处理的ICA和ACA中去甲肾上腺素诱导的最大收缩明显大于PCA和BA中的最大收缩，但各动脉的EC50值无差异。在ACA和MCA中，去氧肾上腺素诱导的收缩大于可乐定诱导的收缩。在普萘洛尔处理的ACA和MCA中，去甲肾上腺素和去氧肾上腺素诱导的收缩被哌唑嗪减弱，但不受育亨宾影响。这些发现表明，牛大脑前部（ACA、MCA和ICA）和后部区域（PCOM、PCA和BA）的脑动脉对去甲肾上腺素的反应明显不同，这可能是由于α/β受体的功能不同所致。在脑前部动脉中主要观察到的胺诱导收缩似乎与α1肾上腺素能受体亚型的激活有关。
