The effects of long-term aerobic exercise on endothelial function in patien
ts with essential hypertension remain unclear, To determine whether endothe
lial function relating to forearm hemodynamics in these patients differs fr
om normotensive subjects and whether endothelial function can be modified b
y continued physical exercise, we randomized patients with essential hypert
ension into a group that engaged in 30 minutes of brisk walking 5 to 7 time
s weekly for 12 weeks (n=20) or a group that underwent no activity modifica
tions (control group, n=7). Forearm blood flow was measured using strain-ga
uge plethysmography during reactive hyperemia to test for endothelium-depen
dent vasodilation and after sublingual nitroglycerin administration to test
endothelium-independent vasodilation. Forearm blood flow in hypertensive p
atients during reactive hyperemia was significantly less than that in normo
tensive subjects (n=17). Increases in forearm blood flow after nitroglyceri
n were similar between hypertensive and normotensive subjects. Exercise low
ered mean blood pressure from 115.7+/-5.3 to 110.2+/-5.1 mmHg (P<0.01) and
forearm vascular resistance from 25.6+/-3.2 to 23.2+/-2.8 mm Hg/mL per minu
te per 100 mL tissue (P<0.01); no change occurred in controls. Basal forear
m blood flow, body weight, and heart rate did not differ with exercise. Aft
er 12 weeks of exercise, maximal forearm blood flow response during reactiv
e hyperemia increased significantly, from 38.4+/-4.6 to 47.1+/-4.9 mL/min p
er 100 mL tissue (P<0.05); this increase was not seen in controls. Changes
in forearm blood flow after sublingual nitroglycerin administration were si
milar before and after 12 weeks of exercise. Intra-arterial infusion of the
nitric oxide synthase inhibitor N-G-monomethyl-L-arginine abolished the en
hancement of reactive hyperemia induced by 12 weeks of exercise. These find
ings suggest that through increased release of nitric oxide, continued phys
ical exercise alleviates impairment of reactive hyperemia in patients with
essential hypertension.