A biphasic response to adenosine in the coronary vasculature of the K +-arrested perfused rat heart

• Published in: European journal of pharmacology 1996-06, Vol.307 (1), p.49-53
• Main Authors: Harden, Fiona A., Harrison, Glenn J., Headrick, John, Jordan, Lindsay R., Willis, Roger J.
• Format: Article
• Language: English
• Subjects: Adenosine - analogs & derivatives; Adenosine - pharmacology; Adenosine A 2A receptor; Adenosine A 2B receptor; Adenosine A 3 receptor; Adenosine Triphosphate - pharmacology; Adenosine-5'-(N-ethylcarboxamide); Animals; Biological and medical sciences; Coronary vasculature, Heart, perfused, rat; Coronary Vessels - drug effects; Coronary Vessels - physiology; Fundamental and applied biological sciences. Psychology; Heart; Heart - drug effects; Heart - physiology; Heart Arrest, Induced; In Vitro Techniques; Male; Muscle Relaxation - drug effects; P 3 purinoceptor; Perfusion; Potassium; Purinergic P1 Receptor Agonists; Rats; Rats, Wistar; Theophylline - analogs & derivatives; Theophylline - pharmacology; Vasodilator Agents - pharmacology; Vertebrates: cardiovascular system
• ISSN: 0014-2999; 1879-0712
• DOI: 10.1016/0014-2999(96)00200-2

Biphasic vasodilatory responses to adenosine and 5′- N-ethylcarboxamidoadenosine (NECA) were observed in the coronary vasculature of K +-arrested perfused rat hearts. Dose-response data for both agonists were best represented by two-site models. For adenosine, two sites with negative log ED 50 (pED 50) values of 8.1 ± 0.1 (mean ± S.E.M) and 5.2 ± 0.1 were obtained, mediating 31 ± 2% and 69 ± 2% of the total response. In the presence of 8-phenyltheophylline, the vasodilatory response to adenosine remained best fitted to a two-site model with pED 50 values of 7.0 ± 0.2 and 5.4 ± 0.2. The relative contribution of each site to the total response remained unchanged. For NECA, pED 50 values of 9.6 +- 0.1 and 6.8 ± 0.2 were obtained, representing 48 ± 3% and 52 ± 3% of the sites, respectively. In contrast, ATP produced a monophasic response with a pED 50 value of 8.8 ± 0.1. These results provide evidence of adenosine receptor and response heterogeneity in the in situ coronary vasculature.