α-ADRENOCEPTOR BLOCKING PROPERTIES OF A NEW ANTIHYPERTENSIVE AGENT, 2-[4-(n-BUTYRYL)-HOMOPIPERAZINE-1-YL]-4-AMINO-6, 7-DIMETHOXYQUINAZOLINE (E-643)

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概要

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• Postsynaptic α-receptor blocking properties of E-643 were studied <I>in vivo</I> and <I>in vitro</I> and compared with these same properties of phentolamine and phenoxy-benzamine. In anesthetized rats, E-643 (i.v.) attenuated pressor response to adrenaline dose-dependently and an adrenaline-reversal was seen with large doses. The <I>in vivo</I> α-adrenoceptor 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 pA<SUB>2</SUB> values for E-643 and phentolamine were 8.60 and 7.65, respectively. The α-blocking effect of E-643 was reversible. E-643 protected α-receptors against irreversible inhibition by phenoxybenzamine. E-643 neither exhibited significant blocking effects on K<SUP>+</SUP>-, Ba<SUP>2+</SUP>- and angiotensin-induced contractions of the aorta nor caused relaxation of the aorta contracted by Ca<SUP>2+</SUP>. These data suggest that E-643 is a specific and competitive inhibitor of noradrenaline at the α-adrenoceptors.

• 社団法人 日本薬理学会の論文

著者

• SHOJI Tadao

  Kawashima Branch-Laboratory, Laboratories of Pharmacology, Eisai Co. Ltd.

• DAIKU Yoshiharu

  Laboratories of Pharmacology, Eisai Co. Ltd.,

• IGARASHI Toshiji

  Laboratories of Pharmacology, Eisai Co. Ltd.,

関連論文

• α-ADRENOCEPTOR BLOCKING PROPERTIES OF A NEW ANTIHYPERTENSIVE AGENT, 2-[4-(n-BUTYRYL)-HOMOPIPERAZINE-1-YL]-4-AMINO-6, 7-DIMETHOXYQUINAZOLINE (E-643)
• COMPARISON OF PRE- AND POSTSYNAPTIC α-ADRENOCEPTOR BLOCKING EFFECTS OF E-643 IN THE ISOLATED VAS DEFERENS OF THE RAT

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