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Nigerian Journal of Physiological Sciences
Physiological Society of Nigeria
ISSN: 0794-859X
Vol. 26, No. 2, 2011, pp. 167-172
Bioline Code: np11025
Full paper language: English
Document type: Research Article
Document available free of charge

Nigerian Journal of Physiological Sciences, Vol. 26, No. 2, 2011, pp. 167-172

 en Effect of chloroquine phosphate and toxic concentrations of lead acetate on Ca2+-ATPase activity in isolates and clones of Plasmodium falciparum check for this species in other resources
Bolaji, O.M.; Happi, T. C.; Oduola, A.M.J. & Bababunmi, E. A.

Abstract

Summary: The basal activity of Ca2+-ATPase in two isolates (NL56, UNC) and two clones (D6, W2) of P.falciparum was assessed. The effects of various concentrations of chloroquine phosphate and toxic concentrations of lead acetate were also evaluated in the clones and strains of P.falciparum. The Ca2+-ATPase activity was measured by monitoring the rate of release of inorganic phosphate from the gamma-position of ATP on spectrophotometer at 820nm wavelength. The various concentrations of chloroquine (3, 6, 9, 12, 18μg/ml) and lead acetate (5, 10, 20, 30, 40μg/ml) on Ca2+-ATPase activity were measured respectively. Chloroquine phosphate inhibited Ca2+-ATPase activity in both the isolates and the cloned strains of P.falciparum in concentration dependent manner. Median Inhibitory concentration of chloroquine (MIC50) estimated from the plot of activity against chloroquine concentration was found to be 2.6g/ml at pH 7.4 for both the isolates and cloned strains examined. Lead acetate at concentrations 5-20μg/ml inhibited Ca2+-ATPase activity in concentration dependent manner in clone W2 (Chloroquine resistant strain) while the same range of concentrations of lead acetate stimulated the activity of the enzyme in clone D6 (Chloroquine sensitive strain).The inhibitory effect of lead acetate on the enzyme in clone D6 was observed at concentrations above 20μg/ml. The result also suggests that lead ions could modulate and moderate calcium ion homeostasis in P. falciparum via its effect on Ca2+-ATPase activity. Also sufficient influx of lead ions into P. falciparum may transform the biochemical or bioenergetics nature of chloroquine sensitive strain of P. falciparum (D6) to that similar to chloroquine resistant strain (W2). In conclusion, inhibition of Ca2+-ATPase activity of P.falciparum may be part of the mechanism of action of chloroquine in its use as chemotherapy for malaria. The study implies that populations simultaneously exposed to lead pollution and malaria infection may experience failure in chloroquine therapy.

Keywords
Plasmodium falciparum; Ca2+-ATPase; Chloroquine phosphate; Lead acetate; Chloroquine resistant strain; Mean Inhibitory Concentration

 
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