Detail of "26839-75-8"

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In vitro determination of the ability of drugs to bind to adrenergic receptors

In vitro determination of the ability of drugs to bind to adrenergic receptors. Neufeld, Arthur H.; Page, Ellen D. (Dep. Ophthalmol. Visual Sci., Yale Univ. Sch. Med., New Haven, Conn., USA). Invest. Ophthalmol. Visual Sci., 16(12), 1118-24 (English) 1977. CODEN: IOVSDA. DOCUMENT TYPE: Journal CA Section: 1 (Pharmacodynamics) Section cross-reference(s): 2 The a- and b-adrenergic receptors were studied by measuring the binding of 3H-labeled dihydroergocryptine [25447-66-9] and 3H-labeled dihydroalprenolol [60106-89-0], resp., to membranes prepd. from homogenized rabbit iris-ciliary bodies. The binding of 3H-dihydroergocryptine was specific for a-adrenergic receptors, since adrenergic agents displaced this radioligand with the following order of potency: phentolamine [50-60-2] > l-epinephrine [51-43-4] 3 l-arterenol d-bitartrate [51-40-1] > l-isoproterenol d-bitartrate [54750-10-6] = dl-propranolol [13013-17-7]. The binding of 3H-dihydroalprenolol was specific for b-adrenergic receptors, since adrenergic agents displaced this radioligand with the following order of potency: propranolol ? isoproterenol 3 epinephrine > norepinephrine ? phentolamine. Clonidine [4205-90-7] and dopamine [51-61-6] bound to the a-adrenergic receptor but had little activity at the b-adrenergic receptor. Timolol [26839-75-8], d-isoproterenol [2964-04-7], and dipivalyl epinephrine [56298-24-9] bound to the b-adrenergic receptor but had little activity at the a-adrenergic receptor. In vitro binding assays for a- and b-adrenergic receptors are useful for studying the mechanism of drug action.

Studies on the mechanism of the antihypertensive effect of

Studies on the mechanism of the antihypertensive effect of .beta.-adrenergic blocking drugs in the spontaneously hypertensive rat. Sweet, Charles S.; Scriabine, Alexander; Wenger, Herbert C.; Ludden, Carl T. (Dep. Pharmacol., Merck Inst. Ther. Res., West Point, Pa., USA). Monogr. Physiol. Soc. Philadelphia, 2(New Antihypertens. Drugs), 227-38 (English) 1976. CODEN: MPPADB. DOCUMENT TYPE: Journal CA Section: 1 (Pharmacodynamics) The antihypertensive activity of timolol [26839-75-8] and propranolol (I) [525-66-6] was examd. in spontaneously hypertensive rats (SHR). The onset in antihypertensive activity occurred on the second day of treatment with timolol (1.25 mg/kg/day orally), and on the third day with I (20 mg/kg/day orally). A central nervous system (CNS) site of action was proposed to explain the antihypertensive effect of .beta.-adrenergic blocking drugs. The peak antihypertensive effect occurred 6 h after intracerebroventricular (ICV) administration of timolol and 24 h after ICV administration of I. Another series of expts. were performed to det. the effects of I (20 mg/kg/day p.o. .times. 4 days) on hindquarter vascular resistance in the anesthetized SHR. Hind-quarters were perfused at const. flow, and the vasoconstrictor response to intra-arterial norepinephrine, epinephrine, and tyramine and the vasodilator response to i.a. isoproterenol were compared in groups of SHR treated with either propranolol or methylcellulose. Both treated groups had nearly identical dose response curves to all vasoconstrictor substances. The vasodilator response to i.a. isoproterenol was significantly attenuated in the I-treated group.