Dipyridamole enhances inhibitory effect of adenosine on neutrophils in human peripheral blood

Abstract

Objective It was known that neutrophils play an important role in ischemic-reperfusion injury. In this study we tested the effect and its mechanism of dipyridamole on neutrophils. Methods Hydrogen peroxide (H 2O 2) production by neutrophils was determined using luminol amplified chemiluminescence and the percentage of activity was calculated by observing the uninhibited peak height. Results Dipyridamole per se produced a concentration-dependent inhibition of H 2O 2 by formyl-MetleuPhe (fMLP)-stimulated neutrophils. Dipyridamole at a low concentration (0.3 μ mol·L −1) that per se affected neutrophils only slightly, enhanced markedly the effects of adenosine on neutrophils. On the other hand, dipyridamole did not alter the inhibitory effect of NECA (5′-N-ethylcarboxamidoadenosine) on neutrophils. However, propentofylline, a known inhibitor of adenosine uptake, also gotten the same result. Conclusion Dipyridamole inhibited the production of H 2O 2 by fMLP-stimulated neutrophils. Dipyridamole at a low concentration enhanced the inhibitory effect of adenosine on neutrophils. The mechanism involved is probably due to the effect of dipyridamole on adenosine uptake.