Measuring pH of the Plasmodium falciparum digestive vacuole by flow cytometry
- Author:
Nurhidanatasha Abu Bakar
- Publication Type:Journal Article
- From:Tropical Biomedicine
2015;32(3):485-493
- CountryMalaysia
- Language:English
-
Abstract:
Studies show that the pH of the malaria parasite’s digestive vacuole (DV) plays a
key role in the physiological functions of this organelle and antimalarial drug accumulation,
and yet is technically difficult to measure. In this study, a flow cytometry-based technique
was developed to measure the DV pH using a ratiometric pH indicator, FITC-dextran loaded
into the DV of saponin-permeabilized parasites. To calculate the DV pH, a standard pH
calibration curve was generated by incubating the saponin-permeabilized cells in buffers
with different pH in the presence of an ionophore, CCCP. The measured average pH of the DV
was 5.27 ± 0.03 that is approximately the same in the parasites observed microscopically by
Hayward et al. (2006) (5.50 ± 0.14) using the same probe. The removal of glucose from the
medium, causing a rapid depletion of parasite ATP, resulted in an alkalization of the DV. The
DV was reacidified upon restoration of glucose to the medium. This technique provides a
rapid, simple and quantitative measurement of the DV pH on a large number of cells. It will
also be useful in future attempts to evaluate the effect of antimalarial drugs (i.e. chloroquineand
artemisinin-based drugs) in pH changes of the DV.
- Full text:W020151207579940786837.pdf
