Local changes in membrane potential intensify neutrophil oxidative burst

The aim of this paper is to study the effects of the pulsed electrical field/current alone or combined with ionomycin, fMLP and PMA, the chemical stimuli that operate through distinctly different activation pathways, on the time course of the oxidative burst response in human neutrophils. Neither the control groups nor the neutrophils treated with electrical field alone showed any increase in oxidative burst activity measured by the luminol-enhanced chemiluminescence technique. It was found that electrical treatment potentiates chemically induced activation with either of the chemical stimulators used. The integrated oxidative burst response--which represents a cumulative amount of oxygen metabolites produced during whole response--was 87% higher in neutrophils treated with a combination of ionomycin and an electric field than in solely ionomycin treated cells, while the peak level of the response was 114% higher. In neutrophils stimulated with fMLP the electrochemical treatment caused a 32% higher integral response as well as a 22% higher peak level compared to the neutrophils treated with chemical stimulant alone. The integrated oxidative burst response in the combined PMA and electric treatment was only 4.7% higher than in the cells treated with PMA alone, and no significant difference in the peak level was found. The results suggest that electric field treatment preferentially stimulates calcium-induced activation with ionomycin rather than calcium-dependent activation with fMLP or PMA.