Inhibition of active oxygen generation by dipyridamole in human polymorphonuclear leukocytes

The effect of dipyridamole on active oxygen generation by human polymorphonuclear leukocytes (PMN) was investigated. Dipyridamole inhibited the production of oxidative metabolites from human PMN stimulated by opsonized zymosan and formyl-methionyl-leucyl-phenylalanine dose and time dependently. To determine whether dipyridamole directly inhibits the production of oxygen metabolites by human PMN, human PMN were preincubated with dipyridamole washed prior to stimulation. Dipyridamole was found to directly inhibit human PMN from generated active oxygen metabolites at therapeutic concentrations. Dipyridamole may possibly be a potential scavenger of active oxygen metabolites since it inhibited active oxygen metabolite production from human PMN very rapidly. Dipyridamole was also found to directly affect the scavenging of active oxygen metabolites generated by opsonized zymosan-stimulated human PMN at therapeutic concentrations. This action of dipyridamole was also noted to be exerted against hydroxyl radicals and superoxide anions produced biochemically by an electron spin resonance spectrometer. It thus follows that dipyridamole may inhibit human PMN active oxygen metabolite generation and affect directly the scavenging of active oxygen metabolites at therapeutic concentrations.