Vasoactive drugs inhibit oxygen radical production of neutrophils

A concentration response study was performed to clarify whether vasoactive drugs, routinely used in intensive care patients, inhibit oxygen radical production of neutrophils. Moreover, in a cell-free system, it was investigated whether these drugs exert free radical scavenging properties. Vasoactive agents were incubated with neutrophils from healthy human volunteers, which were stimulated by N-formyl-methionyl-leucyl-phenylalanine (FMLP) and by opsonized zymosan to produce oxygen radicals, detected by chemiluminescence measurements. Sympathomimetics (epinephrine greater than norepinephrine, dopamine and dobutamine) as well as phosphodiesterase-inhibitors (amrinone and enoximone) inhibited FMLP-induced and zymosan-induced oxygen radical production of neutrophils in a concentration-dependent and drug-specific fashion. With the exception of amrinone, FMLP-induced chemiluminescence of neutrophils was impaired nearly 10-fold more markedly than zymosan-induced chemiluminescence. Glyceryl trinitrate, nifedipine and prostacyclin had no effect on oxygen radical production of neutrophils. In the cell-free system, epinephrine, norepinephrine, dopamine, amrinone and enoximone demonstrated oxygen free radical scavenging properties. This study shows that vasoactive drugs, frequently used in the clinical setting, may suppress oxidative burst after FMLP-receptor stimulation. As demonstrated in the cell-free system, this suppression was, at least in part, due to oxygen radical scavenging.