Neutrophil-derived, Oxygen Free Radical-mediated Cardiovascular Dysfunction

Oxygen free radicals and their metabolites generated from activated neutrophils have been implicated in mediating the cardiovascular dysfunction of such diverse etiologies as myocardial ischemia and reperfusion injury, Gram negative sepsis, myocarditis and acute cardiac allograft rejection, but a direct demonstration of neutrophil derived oxygen free radical mediation of cardiovascular dysfunction has not been accomplished. In this study, we have demonstrated that activation of the canine neutrophil system, in vivo, results in the generation of oxygen free radicals that are capable of disrupting cardiovascular function producing a significant decrease in mean arterial pressure and cardiac index without any significant effect on the conduction system of the myocardium. Neutrophil depletion or pretreatment with superoxide dismutase and catalase inhibited the effects of activated neutrophils. This study provides evidence that neutrophil-derived reduced oxygen intermediates are able to induce severe cardiovascular dysfunction.