PMID: 6113297Dec 1, 1980Paper

alpha-Adrenoceptor blocking properties of a new antihypertensive agent, 2-[4-(n-butyryl)-homopiperazine-1-yl]-4-amino-6,7-dimethoxyquinazoline (E-643)

Japanese Journal of Pharmacology
T ShojiT Igarashi

Abstract

Postsynaptic alpha-receptor blocking properties of E-643 were studied in vivo and in vitro and compared with these same properties of phentolamine and phenoxybenzamine. In anesthetized rats, E-643 (i.v.) attenuated pressor response to adrenaline dose-dependently and an adrenaline-reversal was seen with large doses. The in vivo alpha-adrenoreceptor blocking effect of E-643 was 3.4 times more potent than that of phentolamine. On the other hand, hypotensive action of E-643 was 9.4 times more potent than that of phentolamine. In the isolated rabbit aorta, E-643 blocked noradrenaline-induced contraction of the aorta with a parallel shift of the dose-response curve to the right. The pA2 values for E-643 and phentolamine were 8.60 and 7.65, respectively. The alpha-blocking effect of E-643 was reversible. E-643 protected alpha-receptors against irreversible inhibition by phenoxybenzamine. E-643 neither exhibited significant blocking effects on K+-, Ba2+- and angiotensin-induced contractions of the aorta nor caused relaxation of the aorta contracted by Ca2+. These data suggest that E-643 is a specific and competitive inhibitor of noradrenaline at the alpha-adrenoceptors.

Citations

Jul 1, 1993·European Journal of Drug Metabolism and Pharmacokinetics·A HalabiW Kirch
Jan 1, 1981·European Journal of Clinical Pharmacology·T KawasakiT Omae
Jan 1, 1989·European Journal of Clinical Pharmacology·Y HirataM Ishii
Jan 15, 1993·European Journal of Pharmacology·Y TanakaY Shigeta
Jan 1, 1986·Clinical and Experimental Hypertension. Part A, Theory and Practice·M NakaiY Matsui
Jan 1, 1989·Clinical and Experimental Hypertension. Part A, Theory and Practice·M YoshiokaH Saito
Feb 1, 1997·Prostaglandins, Leukotrienes, and Essential Fatty Acids·S TakadaY Uehara
Jan 6, 2004·Journal of Glaucoma·Hiroshi KobayashiSatoshi Okinami
Jun 29, 1999·Journal of Ocular Pharmacology and Therapeutics : the Official Journal of the Association for Ocular Pharmacology and Therapeutics·Y TamakiK Muta
Feb 15, 1988·Biochemical and Biophysical Research Communications·H OrimoY Ouchi

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