Summary
The present study was an attempt to characterize the adenosine receptor in human coronary arteries, and to establish the dependence of the relaxations mediated by this receptor on a functional endothelium. Human coronary arteries were obtained from organ donors. Adenosine and its analogs (5′-N-ethyl-carboxamido-adenosine, NECA; N6-l-phenylisopropyladenosine, LPIA; 2-chloroadenosine, CAD), all inhibited the contraction induced by 25 mmol/l KCl in a concentration-dependent manner and the order of potency was found to be NECA > CAD > L-PIA > adenosine. These relaxations were antagonized by 8-phenyltheophylline (8PT). At higher concentrations of KCl, the relaxations were attenuated. In rings which relaxed in response to endothelium-dependent relaxing agents (bradykinin and A23187), NECA and CAD produced relaxations similar to those produced in rings which did not show endothelium-dependent responses. The results suggest that the coronary adenosine receptor (probably A2) mediates relaxations which may not be dependent on the relaxing function of the endothelium.
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Sabouni, M.H., Ramagopal, M.V. & Jamal Mustafa, S. Relaxation by adenosine and its analogs of potassium-contracted human coronary arteries. Naunyn-Schmiedeberg's Arch Pharmacol 341, 388–390 (1990). https://doi.org/10.1007/BF00180667
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DOI: https://doi.org/10.1007/BF00180667