Ro 363 hydrochloride, an effective inotropic stimulant, is a potent and highly selective β1-adrenoceptor agonist. Ro 363 hydrochloride is a cardiovascular modulator that reduces diastolic blood pressure and pronounces increases in myocardial contractility[1][2][3].
Isolated perfused heart preparations from guinea-pigs developed arrhythmic contractions following the administration of Ro 363 in doses producing 70-100% of its maximal chronotropic responses[1]. In spontaneously contracted tracheal preparations from the guinea-pig, RO 363 is a full agonist and is approximately half as potent as (-)-Isoprenaline. These effects of RO 363 are due to the activation of a population of β1-receptors in the tissue since RO 363 and (-)-Isoprenaline have the same relative potencies in trachea, cardiac and ileal preparations[2].
In chloralose-anaesthetized cats, Ro 363, when compared to epinephrine (adrenaline), is essentially devoid of arrhythmogenic activity in animals in which cardiac sensitization is induced by U-0882 or halothane[1].
References:
[1]. Maccarrone C, et al. Comparison of the Arrhythmogenic Actions of (-)-Isoprenaline, Dobutamine and the selective beta 1-adrenoceptor agonist, (+/-)-(1-[3',4'-dihydroxyphenoxy] -2-hydroxy-[3",4"-dimethoxy phenethylamino]-propane)-oxalate (Ro 363). Arzneimittelforschung. 1985;35(3):592-8.
[2]. Iakovidis D, et al. In vitro activity of RO363, a beta1-adrenoceptor selective agonist. Br J Pharmacol. 1980 Apr;68(4):677-85.
[3]. Einstein R, et al. Comparison of the cardiac effects of beta-adrenoreceptor agonists in anaesthetised and conscious dogs. J Auton Pharmacol. 1986 Mar;6(1):9-14.