The in vivo examination of the irreversible beta-adrenoceptor antagonist Ro 03-7894 on cardiac rate and contractility.
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| Abstract |
1. Two benzofuran-2-ethanolamines Ro 03-5255 (1-(5-acetylamino-benzofuran-2-yl)-1-hydroxy-2-isopropylaminoethane) and Ro 03-7894 (1-(5-chloracetyl aminobenzofuran-2-yl)-1-hydroxy-2-isopropylaminoethane) which had previously been shown to exhibit respectively competitive and irreversible beta-adrenoceptor antagonism in guinea-pig isolated atria, were compared in vivo using isoprenaline-induced tachycardia of anaesthetized guinea-pigs and heart rate and contractility (dp/dtmax) of open-chest anaesthetized guinea-pigs and of conscious cats. 2. In urethane-anaesthetized guinea-pigs doses of 3 mg/kg, s.c. of both antagonists produced significant blockade of the rate response to an 80% of maximum dose of isoprenaline after 4 h. In other experiments, guinea-pigs were pretreated with the antagonists and the responses to isoprenaline were then monitored. The slopes of the dose-response curves to isoprenaline were depressed for up to 24 h by Ro 03-7894 but this was not so with Ro 03-5255. 3. In conscious cats the course of blockade by Ro 03-7894 was followed in the same animals and was still evident after 48 h. In contrast, the beta-adrenoceptor blockage produced by Ro 03-5255 was not evident 24 h after administration. 4. The persistence of blockade by Ro 03-7894 was consistent with the irreversible mode of action demonstrated in vitro.
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| Authors | C D Nicholson, K J Broadley, D T Burden, I L Natoff |
| Journal | Clinical and experimental pharmacology & physiology (Clin Exp Pharmacol Physiol) 1979 Nov-Dec Vol. 6 Issue 6 Pg. 599-609 ISSN: 0305-1870 [Print] Australia |
| PMID | 42499 (Publication Type: Journal Article) |
| Chemical References |
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