Fig. 2. A, MAP (mean ± SEM) during rest and stress periods. Subjects with high (Hi, based on median split) levels of 5HIAA show a larger increase in MAP than subjects with low (Lo) 5HIAA levels (two-way ANOVA, group-by-period interaction: p < .001). B, Subjects with l/l or l/s genotype show larger MAP increases than s/s subjects (two-way ANOVA, group-by-period interaction: p < .0001).