Dipyridamole inhibition of adenosine metabolism in human blood

The effects of dipyridamole on the metabolism of adenosine were studied in human whole blood. The half-life for adenosine disappearance and the formation of deamination and phosphorylation products were determined by adding [ 3H]adenosine to blood incubating at 37°C. The initial adenosine concentration was 10 nmol/ml blood. Aliquots of blood were removed at specific times following the addition of labelled adenosine. The aliquots were later assayed for adenosine and its products by reverse-phase high pressure liquid chromatography. The half-life for adenosine in undiluted blood was 10 nmol/ml blood. Since these inhibitory concentrations of dipyridamole are on the same order as those achieved therapeutically in man, these data indicate that dipyridamole at therapeutic concentrations causes significant inhibition of adenosine metabolism in whole blood.