Dipyridamole affects myocardial adenosine kinase activity

Abstract

Adenosine kinase (EN 2.7.1.20) from rat and dog heart was purified until it was devoid of adenosine deaminase activity. A stimulation of adenosine kinase activity by dipyridamole (¹) was observed when the enzyme was assayed under optimal conditions. At low substrate concentrations adenosine kinase was inhibited by the drug. It increased the K_m for adenosine sevenfold. The effects of dipyridamole were Mg²⁺-dependent. The adenosine-sparing action of dipyridamole at low substrate concentrations is in keeping with the vasodilatory action of the drug.