The malaria parasite Plasmodium falciparum activates new permeation pathways (NPP) in the host cell membrane of infected human red blood cells (RBCs), which are permeable to anions, cations and a range of organic solutes. It has been suggested from inhibitor and substrate selectivity studies that the NPP may be identical to the volume-activated anion channel (VRAC) present in many mammalian cell types. Here we have tested several known inhibitors of VRAC on the transport of choline and lactate in malaria-infected human RBCs and on parasite growth. Mefloquine, tamoxifen and clomiphene were all without effect on malaria-induced transport at concentrations up to 10 μM and only mefloquine (IC50 = 24 nM) and, to a lesser degree, clomiphene (IC50 = 6.2 μM) inhibited parasite growth below this level. It is concluded that the antimalarial effect of mefloquine does not involve the inhibition of malaria-induced transport via the NPP and there is no evidence at present for VRAC and the NPP being identical.
All Science Journal Classification (ASJC) codes
- Molecular Medicine
- Molecular Biology
- Cell Biology