Receptor-dependent vasocontraction of aorta segments 11-13 weeks old apoE-/- mice exposed to carbon black by i.t. instillation. The response is expressed as the % of the maximal contraction induced by stimulation with a cocktail of K+-PSS, PGF2α, and U-46619. Each point on the curve represents the cumulative response at each concentration of phenylephrine (PE). The data are expressed as the mean and SEM (see graph for n-values). # denotes a significant effect on EC50 compared to the control group (P < 0.05, ANOVA with unequal variance between groups).