CONICET | Buscador de Institutos y Recursos Humanos

During the course of its complex life cycle, the malaria parasite Plasmodium falciparum invades red blood cells (RBCs). The parasite grows and multiplies within the RBCs modifying the membrane structure and biochemical properties of the host cell. Activation of ATP release by RBCs can control vasodilatation and malaria patients show microcirculatory impairments which might be associated altered extracellular ATP (ATPe) homeostasis. Patients with uncomplicated malaria show low parasitemia (4%), so that most circulating RBCs are uninfected RBCs (ui-RBCs). Here, we tested if ui-RBCs undergo a deregulation of ATP homeostasis, with consequences on rheological properties of ui-RBCs.Two methods for isolating ui-RBCs were developed: 1- culture of infected RBCs and ui-RBCs, which were later separated by magnetic columns, and 2- culture of RBCs and ui-RBCs in separated chambers which were connected by a mesh, allowing solute exchange but no physical contact. When stimulated with an adrenergic cocktail, ui-RBCs showed a 4-fold increase of [ATPe], while control RBCs exhibits a 2-fold increase. In both cases, ATPe kinetics was compatible with acute and transient activation of ATP release. There were no differences between ui-RBCs obtained by either of the two isolation methods. When mechanical deformation was imposed to RBCs, ATPe was similar in ui- and control RBCs, displaying a 10-fold increase over basal values. ATPe hydrolysis by ectonucleotidases was upregulated 4-fold in ui-RBCs, when compared to control RBCs, so that ATPe by-products are assumed to accumulate and signal in the extracellular milieu.In short, ui-RBCs showed an altered metabolic balance affecting ATPe regulation with potential consequences on vasodilatation. No physical contact with infected cells was necessary for ui-RBCs to exhibit a deregulation of ATPe homeostasis. With grants from CONICET (PIPC0459), UBA (20020130100027BA), ANPCYT (PICT0327) AND ECOS-Sud-MINCYT (A15S01).