Lim H C, Chong O K, Chan S H
Department of Physiology, Faculty of Medicine, National University of Singapore, Kent Ridge.
Neuropharmacology. 1988 Mar;27(3):243-9. doi: 10.1016/0028-3908(88)90040-8.
The participation of alpha-adrenoceptors in the nucleus reticularis gigantocellularis in the hypotensive, negative inotropic and chronotropic effects induced by guanabenz, was examined in rats anesthetized with pentobarbital sodium (40 mg/kg, i.p.). Pretreatment with alpha-adrenoceptor antagonists yohimbine (10 micrograms), phentolamine (2.5 micrograms) and phenoxybenzamine (20 micrograms), which were injected bilaterally into the nucleus reticularis gigantocellularis, significantly antagonized the cardiovascular suppressant effects normally produced by systemic administration of guanabenz (10 micrograms/kg, i.v.). Pretreatment with prazosin (0.25 microgram) did not affect the vasodepressive, but significantly attenuated the bradycardic actions of guanabenz. The general trend of "antagonization potency" shown by the alpha-adrenergic blockers, against the cardiovascular effects of guanabenz, was in the order: yohimbine greater than phentolamine greater than phenoxybenzamine greater than prazosin. It is concluded that while the alpha 2-adrenoceptors in the nucleus reticularis gigantocellularis are more critically involved in the antihypertensive actions of guanabenz, the possibility exists that alpha 1-adrenoceptors may also participate, in part.
在戊巴比妥钠（40毫克/千克，腹腔注射）麻醉的大鼠中，研究了巨细胞网状核中的α-肾上腺素能受体在胍那苄诱导的降压、负性肌力和变时作用中的参与情况。预先双侧注射到巨细胞网状核中的α-肾上腺素能受体拮抗剂育亨宾（10微克）、酚妥拉明（2.5微克）和酚苄明（20微克），可显著拮抗胍那苄（10微克/千克，静脉注射）全身给药通常产生的心血管抑制作用。预先使用哌唑嗪（0.25微克）对胍那苄的血管舒张作用无影响，但可显著减弱其减慢心率的作用。α-肾上腺素能阻滞剂对胍那苄心血管作用的“拮抗效力”总体趋势为：育亨宾＞酚妥拉明＞酚苄明＞哌唑嗪。结论是，虽然巨细胞网状核中的α2-肾上腺素能受体在胍那苄的降压作用中起更关键作用，但α1-肾上腺素能受体也可能部分参与其中。
