Regular aerobic exercise reduces endothelin-1 mediated vasoconstrictor tone in overweight and obese adults

Abstract

Endothelin (ET)-1-mediated vasoconstrictor tone is elevated in overweight and obese adults, contributing to vasomotor dysfunction and increased cardiovascular disease risk. While the effects of habitual aerobic exercise on endothelium-dependent vasodilation in overweight/obese adults has been studied, little is known regarding ET-1 vasoconstriction. Accordingly, the aims of the present study were to determine: (1) if regular aerobic exercise training reduces ET-1-mediated vasoconstrictor tone in overweight and obese adults; and, if so (2) whether the reduction in ET-1 vasoconstriction contributes to exercise-induced improvement in endothelium-dependent vasodilation in this population. Forearm blood flow (FBF) to intra-arterial infusion of selective ET_A receptor blockade (BQ-123, 100 nmol min⁻¹ for 60 min), acetylcholine (4.0, 8.0 and 16.0 μg/100 ml tissue min⁻¹) in the absence and presence of ET_A receptor blockade and sodium nitroprusside (1.0, 2.0 and 4.0 μg/100 ml tissue min⁻¹) were determined before and after a 3-month aerobic exercise training intervention in 25 (16M/9F) overweight/obese (BMI: 30.1 ± 0.5 kg m⁻²) adults. The vasodilator response to BQ-123 was significantly lower (∼25%) and the FBF responses to acetylcholine were ∼35% higher after exercise training. Before the exercise intervention the co-infusion of acetylcholine+BQ-123 resulted in a greater vasodilator response than acetylcholine alone; however, after the exercise intervention the FBF response to acetylcholine was not significantly increased by ET_A receptor blockade. These results demonstrate that regular aerobic exercise reduces ET-1-mediated vasoconstrictor tone in previously sedentary overweight and obese adults. Moreover, decreased ET-1 vasoconstriction is an important mechanism underlying the aerobic exercise-induced improvement in endothelium-dependent vasodilator function in overweight/obese adults.

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