Adenosine transporters in chromaffin cells

Abstract

Chromaffin cells from bovine adrenal medulla are a useful model to approach adenosine transport and metabolism in neural cells. Dipyridamol has been shown to be an adenosine transport inhibitor with high affinity. To quantify the adenosine transporters a labelled dipyridamol analogue, [¹⁴C]dipyridamol acetate, was synthesized. This compound had a K _i = 5.3 ± 0.43 nM according to the Dixon method, and 4.58 ± 0.46 nM when the receptor number molarity was taken into account showing, like dipyridamol, a non‐competitive mechanism. The high‐affinity receptors present in chromaffin cells showed a K _d = 6.8 ± 0.8 nM and the receptor number was 630000 ± 40000 per cell.