Chloroquine-resistant Plasmodium falciparum: effect of substrate on chloroquine and amodiaquin accumulation.

Glucose stimulates the high-affinity processes of chloroquine and amodiaquin accumulation in owl monkey erythrocytes infected with a chloroquine-susceptible strain of Plasmodium falciparum. Although these erythrocytes have greater ability to accumulate amodiaquin than chloroquine, glucose has relatively less effect on amodiaquin accumulation than on chloroquine accumulation. In contrast to these findings with chloroquine-susceptible P. falciparum, glucose stimulates amodiaquin but not chloroquine accumulation in erythrocytes infected with chloroquine-resistant P. falciparum. This lack of function of a substrate-dependent component of chloroquine accumulation distinguishes chloroquine-resistant from chloroquine-susceptible P. falciparum.