Plasmodium berghei-infected mice: lack of effect of meclizine and cimetidine on the development of pulmonary oedema.

The involvement of histaminergic mechanisms in the pathogenesis of pulmonary oedema observed in Plasmodium berghei-infected mice was investigated. Histamine concentrations in plasma and whole blood of infected and normal mice were determined by radioenzymatic assay during the seven days of the infection. Elevated plasma and whole blood histamine levels were found at the last stages of infection (sixth day and seventh day after ip injection of parasitized erythrocytes), showing a close temporal correlation between the development of oedema and the elevation of the circulating histamine concentrations. However, the treatment of infected mice with the H1- or H2-receptor antagonists, meclizine or cimetidine, did not change the development of pulmonary oedema. The absence of effects of H1- and H2-receptor blockers on this model is a suggestive evidence that histamine does not contribute to P. berghei-induced pulmonary oedema in mice.