Autoradiographic localization of adenosine uptake sites in guinea pig brain using [3H]dipyridamole

Tritiated dipyridamole, a specific adenosine uptake inhibitor binds in a saturable and reversible fashion to high-affinity receptor sites in guinea pig brain sections (Kd = 10 +/- 1.5 nM; Bmax = 650 +/- 100 fmol/mg prot.). The anatomical distribution of [3H]dipyridamole binding sites obtained with autoradiographic techniques shows a widespread but heterogeneous distribution of the binding sites throughout the whole guinea pig brain. Very high densities of binding sites are observed in the cerebellar cortex (molecular layer), the pyriform cortex, the superior colliculus (superficial layer), the supraoptic nucleus and the nucleus of the tractus solitarius. The anatomical characterization of the adenosine uptake site, using [3H]dipyridamole as a probe, may be useful to determine the functional role of adenosine in the brain.