Effect of nifedipine on calcium status and chemiluminescence response of phagocytes during Plasmodium berghei infection in mice.

The macrophages and neutrophils from nifedipine-treated mice, both Plasmodium berghei-infected and uninfected, showed suppressed capacity to generate oxygen free radicals as compared with untreated controls. Nifedipine treatment did not affect resting state free calcium levels in these cells. But the rise in intracellular calcium levels of macrophages and neutrophils following P. berghei infection was significantly less (P < 0.05) in nifedipine-treated mice as compared with untreated groups at various parasitaemia levels. Probably this reflects a more potent effect of nifedipine on these cells in the depolarized state. Similarly, the rise in intracellular calcium levels of these cells following formyl-Met-Leu-Phe (fMLP) stimulation was also significantly less in nifedipine-treated groups than in untreated controls at different parasitaemia levels. A positive correlation between this fMLP-stimulated rise in calcium levels and the chemiluminescence response of macrophages and neutrophils was observed in nifedipine-treated and untreated groups at various parasitaemia levels. Thus the respiratory-burst responses of these cells during P. berghei infection depend on the calcium homeostasis in the cells. The disturbances of the calcium-regulating mechanisms by nifedipine treatment resulted in subnormal phagocytic cell responses which lead to more severe and rapidly fatal P. berghei infection in these animals.