Evidence that the positive inotropic effects of the alkylxanthines are not due to adenosine receptor blockade

• Published in: British journal of pharmacology Vol. 81; no. 2; pp. 401 - 407
• Main Authors: Collis, M.G., Keddie, J.R., Torr, S.R.
• Format: Journal Article
• Language: English
• Published: Oxford, UK Blackwell Publishing Ltd 01.02.1984; Nature Publishing; Nature Publishing Group
• Subjects: Animals; Atenolol - pharmacology; Biological and medical sciences; Cardiotonic agents; Cardiovascular system; Dogs; Female; Guinea Pigs; Heart Atria - drug effects; Heart Rate - drug effects; Hydrogen-Ion Concentration; In Vitro Techniques; Male; Medical sciences; Myocardial Contraction - drug effects; Pharmacology. Drug treatments; Receptors, Cell Surface - antagonists & inhibitors; Receptors, Purinergic; Xanthines - pharmacology; Heart; Cardiotonic agent; Contractility
• DOI: 10.1111/j.1476-5381.1984.tb10092.x
• ISSN: 0007-1188

1 We investigated the possibility that the positive inotropic effects of the alkylxanthines are due to adenosine receptor blockade. 2 The potency of 8‐phenyltheophylline, theophylline and enprofylline as adenosine antagonists was assessed in vitro, using the guinea‐pig isolated atrium, and in vivo, using the anaesthetized dog. 3 The order of potency of the alkylxanthines as antagonists of the negative inotropic response to 2‐chloroadenosine in vitro, and of the hypotensive response to adenosine in vivo was 8‐phenyltheophylline > theophylline > enprofylline. 4 The order of potency of the alkylxanthines as positive inotropic and chronotropic agents in the anaesthetized dog was enprofylline > theophylline > 8‐phenyltheophylline. 5 The results of this study indicate that the inotropic effects of the alkylxanthines in the anaesthetized dog are not due to adenosine receptor blockade.