Niemand, Jandeli2024-06-062024-06-062024-09-072024-06-04*S2024http://hdl.handle.net/2263/96331DOI: https://doi.org/10.25403/UPresearchdata.25958974.v1Dissertation (MSc (Biochemistry))--University of Pretoria, 2024.While malaria is a treatable disease caused by Plasmodium parasites, resulting in worldwide mortality. Plasmodium falciparum parasites are vulnerable to changes in intracellular ion concentrations. The parasite Na+/H+-ATPase (PfATP4) responsible for the simultaneous efflux of Na+ and the influx of H+ is targeted by chemically diverse antiplasmodial compounds, while triaminopyrimidine resistance is associated with mutations in a V-type H+-ATPase. In P. falciparum parasites, a high intracellular K+ concentration is maintained by the influx of K+ through K+ channels, against the concentration gradient due to a highly negative membrane potential. Given that K+ is the most abundant intracellular cation, it is possible that changing intracellular K+ levels would prevent parasite proliferation. Any changes in the intracellular K+ also affect the membrane potential, ultimately leading to cell death. Previous whole-cell proliferation assays showed that putative K+ channel inhibitors and ionophores inhibit proliferation, but these studies did not test the antiproliferative effects with changes in intracellular K+. We found that 250 nM DiBAC4(3) provided a high fluorescent signal in isolated asexual P. falciparum trophozoites after 30 min incubation. This condition resulted in a signal-to-noise of 119.28 and a Z’-factor of 0.83 and was used for further analysis of changes in the parasite’s membrane potential after treatment with inhibitors. APG-1 (5 μM) resulted in the highest signal-to-background ratio after 60 minutes, that also resulted in high signal-to-noise ratios (276.26) and a Z’-factor of 0.89. Therefore, the two fluorescent probes could successfully be detected in P. falciparum parasites and subsequently evaluate changes in Δψ and intracellular K+.en© 2023 University of Pretoria. All rights reserved. The copyright in this work vests in the University of Pretoria. No part of this work may be reproduced or transmitted in any form or by any means, without the prior written permission of the University of Pretoria.UCTDPlasmodiumMembrane potentialFluorescent dyesPotassiumDissertationu1707539510.25403/UPresearchdata.25958974