A comparison of the properties of prenalterol and corwin at β₁‐ and β₂‐adrenoreceptors in vitro

Abstract

1. The affinities and efficacies (relative to isoprenaline) of prenalterol and corwin at beta 1- and beta 2-adrenoreceptors, have been determined in isolated cardiac and vascular tissues respectively. 2. Prenalterol and corwin have similar affinities for cardiac beta 1-adrenoreceptors. The affinity of prenalterol for beta 2-adrenoreceptors is approximately 10 times lower than for beta 1-adrenoreceptors; that for corwin is approximately 100 times lower than for beta 1-adrenoreceptors. 3. The efficacies of prenalterol and corwin, relative to isoprenaline, at beta 1 and beta 2-adrenoreceptors, are similar. 4. The greater selectivity of corwin compared with prenalterol, as an agonist at beta 1-adrenoreceptors, is a reflection of its lower affinity for beta 2-adrenoreceptors.

Selective and full β1‐adrenoceptor agonist action of a catechol derivative of denopamine (T‐0509) in the guinea‐pig cardiac muscle and trachea: comparison with denopamine, xamoterol and isoprenaline

“…PI-Adrenoceptor stimulation is known to cause positive inotropic action through activation of adenylate cyclase (Lemoine et al, 1989a,c). The orally-active cardiotonic agents, denopamine and xamoterol, are highly selective P1-adrenoceptor agonists with partial agonist properties (Nagao et al, 1984;Narita et al, 1986;Yokoyama et al, 1988;Lemoine et al, 1989a;Gurden et al, 1989) and have been introduced recently for the treatment of patients with congestive heart failure (Kino et al, 1983;Ikeda et al, 1987;Furlong & Brogden, 1988). Denopamine causes positive inotropic effects with small increases in heart rate and in myocardial oxygen consumption in both dogs and man (Thormann et al, 1985).…”

Desensitization and functional antagonism by β‐adrenoceptor and muscarinic receptor agonists, respectively: a comparison with receptor alkylation for calculation of apparent agonist affinity

“…Thirdly, an irreversible fiadrenoceptor antagonist, bromoacetylalprenololmenthane (BAAM), was available with which to compare directly apparent KD values calculated by desensitization. Prenalterol, an agonist of low relative efficacy, was employed because (a) its affinity at fl-adrenoceptors has been measured by both functional and radioligand binding methods (Kenakin & Beek, 1982;Kenakin, 1987;Gurden et al, 1989), and (b) errors involved in the estimation of the apparent KD by the method of Furchgott (1966) for partial agonists are less than those associated with full agonists (Eglen et al, 1987;Leff et al, 1990a,b). A second aspect of this paper concerns functional antagonism.…”