Fig. 4.

Average data for SSNA responses to activation of the baroreflex produced by decreases in arterial pressure. Seven doses of sodium nitroprusside were injected intravenously in order of increasing dose and the blood pressure decrease was averaged within groups at each individual dose (SNP, 0.5–13 μg/kg iv). SSNA activation was greater in sedentary (n = 9, ●, dashed line) compared with active (n = 9, ○, solid line) animals. Average reductions in blood pressure at each dose were similar in magnitude between groups by 2-way repeated-measures ANOVA. There was an overall effect of physical activity level on SSNA responses to various levels of MAP, and there was an interaction between physical activity level and decreases in MAP. *P < 0.05 for individual points.