Figure 5: Variations in tolerance to sodium nitroprusside (6 mg/kg, i.p.) as assessed by the percent of mortality at each of the six circadian dosing times (1, 5, 9, 13, 17, and 21 HALO) in a total of 72 Swiss albino male and female mice aged 8 weeks. Each point represents the mean SEM of four independent experiments. The black bar corresponds to the dark period. Best drug tolerance occurred, irrespective to the gender, when the drug was injected in the light phase (during the animal's rest span).