Plasmodium falciparum Na+/H+ exchanger activity and quinine resistance.

Mutations in the Plasmodium falciparum pfcrt gene cause resistance to the 4-amino quinoline chloroquine (CQ) and other antimalarial drugs. Mutations and/or overexpression of a P. falciparum multidrug resistance gene homologue (pfmdr1) may further modify or tailor the degree of quinoline drug resistance.

Novel, rapid, and inexpensive cell-based quantification of antimalarial drug efficacy.

We report on the development of a new SYBR Green I-based plate assay for analyzing the activities of antimalarial drugs against intraerythrocytic Plasmodium falciparum. This assay is considerably faster, less labor-intensive, and less expensive than conventional radiotracer (e.g.

Drug resistance-associated pfCRT mutations confer decreased Plasmodium falciparum digestive vacuolar pH.

Elucidating the altered physiology of various chloroquine resistant (CQR) strains of Plasmodium falciparum is essential for understanding the molecular basis of CQR. In this study, we have devised several new methods for analyzing digestive vacuolar (DV) pH for individual intraerythrocytic parasites under continuous perfusion. These use controlled illumination power and novel data acquisition software, and are based on either acridine orange (AO) emission spectra or ratiometric 5-(and 6-)carboxy-2',7'-dimethyl-3'-hydroxy-6'-N-ethylaminospiro [isobenzofuran-1(3H),9'-(9H)xanthen]-3-one (DM NERF) excitation.