Essential hypertension is associated with impairments in vascular function and sympathetic nerve hyperactivity; however, the extent to which the lower limbs are affected remains unclear. We examined the leg vascular responsiveness to infusion of acetylcholine (ACh), sodium nitroprusside (SNP), and phenylephrine (PEP) in 10 hypertensive men [HYP: age 59.5 ± 9.7 (means ± SD) yr; clinical and nighttime blood pressure: 142 ± 10/86 ± 10 and 141 ± 11/83 ± 6 mmHg, respectively; and body mass index (BMI): 29.2 ± 4.0 kg/m2] and 8 age-matched normotensive counterparts (NORM: age 57.9 ± 10.8 yr; clinical and nighttime blood pressure: 128 ± 9/78 ± 7 and 116 ± 3/69 ± 3 mmHg, respectively; and BMI: 26.3 ± 3.1 kg/m2). The vascular responsiveness was evaluated before and after 6 wk of 10-20-30 training, consisting of 3 × 5 × 10-s sprint followed by 30 and 20 s of low- to moderate-intensity cycling, respectively, interspersed by 3 min of rest. Before training, the vascular responsiveness to infusion of SNP was lower (P < 0.05) in HYP compared with NORM, with no difference in the responsiveness to infusion of ACh and PEP. The vascular responsiveness to infusion of SNP and ACh improved (P < 0.05) with training in HYP, with no change in NORM. With training, intra-arterial systolic blood pressure decreased (P < 0.05) by 9 mmHg in both HYP and NORM whereas diastolic blood pressure decreased (5 mmHg; P < 0.05) in HYP only. We provide here the first line of evidence in humans that smooth muscle cell vasodilator responsiveness is blunted in the lower limbs of hypertensive men. This impairment can be reversed by 10-20-30 training, which is an effective intervention to improve the responsiveness of smooth muscle cells in men with essential hypertension.
Keywords: blood pressure; high-intensity interval training; vascular function; vasoconstriction; vasodilation.