Autoradiographic localization of adenosine A1 receptors in rat brain using [3H]XCC, a functionalized congener of 1,3-dipropylxanthine.

Quantitative autoradiography was used to visualize the anatomical distribution of adenosine receptors labeled by the carboxylic acid congener of 1,3-dipropylxanthine, [3H](8-(p-carboxymethyloxy)phenyl-1,3-dipropylxanthine)([3H]XCC ) in the rat brain. [3H]XCC was observed to specifically bind to rat brain sagittal sections in a heterogeneous pattern. Saturation experiments revealed that [3H]XCC binds with nanomolar affinity to 20-microns frozen tissue sections with the highest binding densities occurring in the hippocampus and cerebellum. Both the binding characteristics and regional receptor distribution obtained with [3H]XCC demonstrate the potential usefulness of this new ligand in the study of adenosine A1 receptors.