Heme oxygenase and related indices in chloroquine-resistant and -sensitive strains of Plasmodium berghei.

Chloroquine-resistant (CQR) and -sensitive (CQS) Plasmodium berghei K173 strains possessed significant activities of heme oxygenase, biliverdin reductase and heme polymerase. Heme oxygenase and biliverdin reducatase activities of CQR were significantly higher (7-10 fold) as compared to that of CQS P. berghei, whereas heme polymerase showed a reverse trend (two-fold decrease). However, a 10-fold increase in heme, three-fold increase in ferriprotoporphyrin IX and a two-fold increase in hemozoin levels were noted in CQS as compared to CQR strains of P. berghei. This study suggests the importance of heme oxygenase and related components in the biochemical regulation of malaria parasites and in understanding the mechanism of the acquisition of chloroquine resistance.