Figure 1

Survival of L. (V.) braziliensis and L.(L.) amazonensis promastigotes in increasing concentrations of NO ^• measured by Thymidine incorporation (A and B) and colorimetric MTT assay (C and D). Promastigotes in HBSS pH 5.0 were exposed to increasing NaNO₂ concentrations (0.25–16 mM) for 4 hours. Viability was measured by incorporation of ³H-TdR or conversion of MTT of formazan as described in the Methods section. Data in panels A and B represent mean ± SEM percentage survival for (1A) 8 resistant L. (L.) amazonensis and two resistant L. (V.) braziliensis isolates, (1B) two susceptible L. (L.) amazonensis and 4 susceptible L. (V.) braziliensis isolates as measured by thymidine incorporation. Data in panels C and D represent the mean ± SEM MTT conversion for (1C) 3 NO^•- resistant L. (L.) amazonensis and 2 NO^•-resistant L. (V.) braziliensis isolates, or (1D) 2 susceptible L. (L.) amazonensis and 12 susceptible L. (V.) braziliensis isolates.