Co-ordinated stage-dependent enhancement of Plasmodium falciparum antioxidant enzymes and heat shock protein expression in parasites growing in oxidatively stressed or G6PD-deficient red blood cells

Table 3 PPP flux in trophozoites growing in oxidatively stressed normal RBCs and in G6PD-deficient RBCs

	Sample	Treatment	PPP flux	-fold increase
A	Trophozoites growing in normal RBCs	nil	5.28 ± 0.84 n = 4	1
B	Trophozoites growing in oxidatively stressed normal RBCs	low XO/X b	37.4 ± 4.5 n = 3	7.1
C	Trophozoites growing in G6PDdeficient RBCs	nil	10.1 ± 1.3 n = 4	1.9

PPP flux was measured in Sendai-virus treated trophozoites growing in normal RBCs (A), oxidatively stressed RBCs (B) and G6PD-deficient RBCs (C). Trophozoite stage parasites were isolated from host RBCs by Sendai-virus treatment and incubated in RPMI 1640 without NaHCO3, but containing 1 μCi/ml D- [1-¹⁴C] glucose at 5% haematocrit. After 90 min of preincubation at 37°C, PPP flux was measured by quantifying produced [¹⁴C]-CO2 as indicated (see Methods). Production of [¹⁴C]-CO2 is expressed as μmol/10¹⁰ cells/h at 37°C. Mean values ± SD of n separate experiments as indicated. Significance of experiments: A vs B; A vs C; and B vs C, p < 0.001 ^bLow XO/X: XO 0.1 mU/ml, see legend to Table 2.

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