Fig. 5.

Average data for MAP responses to phenylephrine (PE; 0.5–13 μg/kg iv) following ganglionic blockade with hexamethonium (30 mg/kg iv) and methyl-atropine (1 mg/kg). Activation of α₁-adrenergic receptors with PE produced dose-dependent increases in MAP in both groups but the response was significantly enhanced in sedentary (n = 6, ●, dashed line) vs. active (n = 9, ○, solid line) animals. Two-way repeated-measures ANOVA showed an overall effect of physical activity level and an interaction between physical activity level and doses of PE (P < 0.05 both); *P < 0.05 specific difference between MAP responses at individual doses.