Chloroquine Sensitivity and Pigment Formation in Rodent Malaria

The degree of selective uptake of chloroquine by P. berghei yoeli and P. berghei CR in the mouse is inversely related to the level of resistance demonstrable and does not depend on previous or concurrent exposure to the drug. Chloroquine sensitive P. berghei NYU-2 when passed into the rat, exhibits an increased tolerance to chloroquine, behaving in this respect like P. berghei yoeli in the mouse. However, it accumulates chloroquine-¹⁴C to an essentially identical degree as the same strain in the mouse, which is extremely sensitive to chloroquine. The decrease or disappearance of pigment in P. berghei NYU-2 when passed into the rat, ite growth in the presence of chloroquine and may not have any direct relationship to the mechanism(s) of resistance.