A Study of Calcium Dynamics in Infected Erythrocytes of Nigerian Children with Plasmodium falciparum Malaria

This study was carried out to determine ghost membrane Ca2+ATPase activity in the infected erythrocytes as a correlate of intraerythrocytic Ca2+ content, parasite maturation and age. In this study, 32 blood samples from children (mean age = 5.8 year) with P. falciparum parasitaemia were analyzed microscopically with erythrocytes submitted for ghost membrane preparation by hypotonic lysis and resealing, membrane Ca2+ATPase activity (measured as micromole of inorganic phosphate liberated from ATP substrate per hour) and intracellular calcium content determination by spectrophotometric methods. The infected erythrocytes were observed to harbour parasites at the ring (56.3%), trophozoite+schizont (34.4%) and gametocyte (9.3%) stages of development (χ2 = 11.2; p = 0.004) with geometric mean parasite density of 9786.9, 14064.2 and 8450.5 parasites μL￣1, respectively (p<0.05). Compared to the control (n = 10, mean age = 6.3 year), a significant (p<0.05) 1.9-3.9 folds increase in intracellular calcium ion (0.615 vs. 1.17-2.37 μg mL￣1) and 1.4-2.0 folds decrease in erythrocyte ghost membrane Ca2+ATPase (0.648 vs. 0. 317-0.475 U mg protein) were found in the infected erythrocytes. These alterations were further found to increase with parasite maturation independent of age with inverse calcium-Ca2+ATPase relationship (r = -0.93; p<0.05). The results of this study have revealed lowered erythrocyte membrane calcium pump activity as a contributor to parasite maturation-dependent intracellular calcium elevation in children with Plasmodium falciparum malaria