Nifedipine affects neutrophil functions by a non-calcium-mediated mechanism

Cardiac disorders are known to be associated with neutrophil infiltration. The central role of calcium in modulating neutrophil functions prompted us to examine whether Ca2+ channel blockers could affect vital neutrophil functions in mice. In vitro exposure of mice neutrophil to nifedipine resulted in inhibition of superoxide production in a dose-dependent manner. However, the inhibition of calcium uptake elicited by nifedipine did not appear to account for the observed effect since the extracellular Ca2+ enrichment and depletion did not produce a significant reversal of inhibition. In addition, there was significant inhibition (P less than 0.01) of nicotinamide adenine dinucleotide phosphate reduced (NADPH) oxidase activity. Cytosolic-free Ca2+, as measured by Quin-2AM fluorescence, showed no significant change indicating that the effect was independent of inhibition of Ca2+ influx. The hypothesis was substantiated by loss of neutrophilic functions following long-term administration of nifedipine. Our data indicate that nifedipine impairs neutrophil functions and support the hypothesis that Ca2+ antagonists also affect cellular functions by non Ca2+ mediated processes.