Plasmodium falciparum and Plasmodium berghei: effect of magnesium on the development of parasitemia.

The in vitro growth of Plasmodium falciparum was reduced by 35 and 43% through high concentrations (5 mmole/liter) of magnesium in RPMI medium and magnesium-free medium, respectively, after 48 hr, whereas no significant inhibition could be observed under these conditions after 24 hr cultivation in the respective medium. Levels of magnesium between 0.5 and 3 mmole/liter showed no inhibitory effect on the in vitro growth of P. falciparum even after long-term exposure for 7 days. The 50 and 90% chloroquine inhibitory concentrations of the chloroquine-resistant strain K1 after 24 hr were reduced to some extent in the presence of magnesium at 5 mmole/liter, but less than in the presence of verapamil at 10 mumole/liter, which showed intrinsic activities at this concentration and which completely reversed resistance. However, high physiologic magnesium plasma levels were associated with a significantly longer survival time of NMRI mice infected with P. berghei strain ANKA, compared to normal physiological plasma magnesium levels. It is concluded that in the case of clinically symptomatic magnesium deficiency, supplementation of magnesium will not aggravate concomitant plasmodial infections and therefore should not be withheld.