Pharmacological properties of tetrahydropapaveroline

Abstract

Tetrahydropapaveroline (thp) exerts β-sympathomimetic effects similar to those of isoprenaline. On guinea-pig isolated atria, thp elicits positive inotropic and chronotropic activities which are not abolished by previous reserpinization of the animals; on isolated mammalian heart these effects are associated with an increase in coronary flow. In the dog, thp increases myocardial contractile force and rate, elicits a hypotensive effect and stimulates respiratory activity in normal and reserpinized animals; when injected intra-arterially the drug causes vasodilatation. All the effects are prevented by the β-adrenergic blocking agents propranolol, dichloroisoprenaline and pronethalol. Structure-activity relationships between tetrahydroisoquinoline derivatives and their open-ring phenylethylamine congeners, which are closely related to sympathomimetic drugs, are discussed.