Binding affinities of 28 adenosine analogs at A1 adenosine receptors (rat whole brain membranes, [3H]N6-cyclohexyladenosine, CHA), and at A2 adenosine receptors (rat striatal membranes, [3H]NECA) were compared to their EC25 values for decreasing heart rate and increasing coronary flow in the isolated rat heart. Heart rate (an A1 response) correlated with A1 binding affinity (r2=0.71, p<0.0001) but not with A2 binding affinity (r2=0.007, n.s.); conversely, coronary flow (an A2 response) correlated with A2 binding affinity (r2=0.83, p<0.0001) but not with A1 binding affinity (r2=0.05, n.s.). These results confirm that the brain A1 and A2 receptors, studied by binding methods, bear close similarities to their respective counterparts in the heart, studied by means of functional responses. © 1987.
Hamilton, H. W., Taylor, M. D., Steffen, R. P., Haleen, S. J., & Bruns, R. F. (1987). Correlation of adenosine receptor affinities and cardiovascular activity. Life Sciences, 41(20), 2295–2302. https://doi.org/10.1016/0024-3205(87)90542-X