Detail of "23256-50-0"

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Comparison of agonistic and antagonistic actions of guanabenz and guanfacin on a1- and a2-adrenoceptors in isolated smooth muscles

Comparison of agonistic and antagonistic actions of guanabenz and guanfacin on a1- and a2-adrenoceptors in isolated smooth muscles. Takeuchi, Kouichi; Kogure, Miki; Hashimoto, Takao (Dep. Pharmacol., Meiji Coll. Pharm., Tokyo 154, Japan). Jpn. J. Pharmacol., 43(3), 267-75 (English) 1987. CODEN: JJPAAZ. ISSN: 0021-5198. DOCUMENT TYPE: Journal CA Section: 1 (Pharmacology) The effects of guanabenz acetate [23256-50-0], guanfacine [29110-47-2] and clonidine [4205-90-7] on a-adrenoceptors were investigated in isolated rat vas deferens and rabbit aortic strip. All 3 drugs at low concns. (10-9-10-8M) caused inhibition of twitch responses of the rat vas deferens induced by nerve stimulation. These effects were competitively antagonized by yohimbine. Guanfacine and clonidine at relatively high concns. (10-6-10-4M) produced contractions of the rat vas deferens which were antagonized by prazosin. These contractile responses were not much affected by denervation. 4205-90-7 and 29110-47-2 which are cas registry numbers of chemicals are mentioned. Prazosin-sensitive contractions by guanfacine and clonidine were also obsd. in the rabbit aortic strip, which were not affected by reserpine pretreatment. In both tissues, the intrinsic activity of guanfacine was almost identical to that of L-norepinephrine bitartrate whereas that of clonidine was less than one half. Guanabenz and clonidine showed a comnpetitive antagonistic effect against norepinephrine and L-phenylephrine in both the rat vas deferens and rabbit aorta, the antagonisms being similar in potency. The results indicate that all 3 drugs are potent agonists on the presynaptic a2-adrenoceptor. In contrast, on the postsynaptic a1-adrenoceptor, guanfacine and guanabenz showed only agonistic and antagonistic actions, resp., whereas clonidine exhibited partial agonistic characteristics. .

Interactions between guanabenz and clonidine in their cardiovascular effects in the rat

Interactions between guanabenz and clonidine in their cardiovascular effects in the rat. Ong, B. T.; Chan, Samuel H. H. (Fac. Med., Natl. Univ. Singapore, Kent Ridge 0511, Singapore). Exp. Neurol., 86(1), 105-12 (English) 1984. CODEN: EXNEAC. ISSN: 0014-4886. DOCUMENT TYPE: Journal CA Section: 1 (Pharmacology) In Sprague-Dawley rats anesthetized with pentobarbital sodium (40 mg/kg, i.p.), guanabenz acetate [23256-50-0] and clonidine [4205-90-7] exhibited mutually interactive effects on the cardiovascular system. Pretreatment with either antihypertensive agent (5 or 10 mg/kg, i.v.) significantly potentiated both the degree and duration of the initial elevation in arterial pressure and cardiac contractility promoted by the other compd. (10 mg/kg, i.v.). On the other hand, discernible antagonization existed mutually for their delayed hypotensive, as well as neg. inotropic and chronotropic actions. Furthermore, these circulatory changes displayed comparable trends under parallel drug interaction schemes, as revealed by correlation coeff. evaluations. Apparently, guanabenz and clonidine may share a common mechanism(s) in their cardiovascular actions.