Tung C S, Goldberg M R, Hollister A S, Robertson D
Department of Pharmacology, National Defense Medical Center, Taipei, Taiwan.
Brain Res. 1988 Jul 19;456(1):64-70. doi: 10.1016/0006-8993(88)90347-2.
We compared the effects of alpha 2- and beta-adrenoreceptor blockade on the central actions of catecholamines and metabolites of alpha-methyldihydroxyphenylalanine, epinephrine, alpha-methylnorepinephrine, and alpha-methylepinephrine were studied. I.c.v. and nucleus tractus solitarii (NTS) injections were carried out under anesthesia. Following i.c.v. injection, both epinephrine and methylepinephrine rapidly reduced blood pressure and heart rate, but the effects of methylnorepinephrine occurred somewhat later. Following microinjection into the nucleus of the solitary tract, epinephrine, methylepinephrine, and methylnorepinephrine all caused hypotension and bradycardia. The hypotensive effects of all 3 amines in the NTS were attenuated in additive fashion by yohimbine, an alpha 2 adrenoreceptor antagonist, and timolol, a beta-adrenoreceptor antagonist, whereas only yohimbine attenuated the bradycardia. The combination of yohimbine and timolol abolished the effects of the amines. These data suggest that in the NTS both alpha 2 and beta adrenoreceptor stimulation contribute to the hypotensive effects of these amines, but that only alpha 2 adrenoreceptors are principally involved in the heart rate response.
我们比较了α₂和β肾上腺素能受体阻断对儿茶酚胺中枢作用的影响，并研究了α-甲基二羟基苯丙氨酸、肾上腺素、α-甲基去甲肾上腺素和α-甲基肾上腺素的代谢产物。在麻醉下进行脑室内（i.c.v.）和孤束核（NTS）注射。脑室内注射后，肾上腺素和甲基肾上腺素均迅速降低血压和心率，但去甲肾上腺素的作用出现稍晚。向孤束核微量注射后，肾上腺素、甲基肾上腺素和去甲肾上腺素均引起低血压和心动过缓。在NTS中，这三种胺类的降压作用均可被α₂肾上腺素能拮抗剂育亨宾和β肾上腺素能拮抗剂噻吗洛尔以相加的方式减弱，而只有育亨宾能减弱心动过缓。育亨宾和噻吗洛尔联合使用可消除胺类的作用。这些数据表明，在NTS中，α₂和β肾上腺素能受体的刺激均有助于这些胺类的降压作用，但只有α₂肾上腺素能受体主要参与心率反应。
