Oxidative stress impairs endothelial function in nondipper hypertensive patients.
OBJECTIVE
Essential hypertension, as well as other established cardiovascular risk factors, is associated with endothelial dysfunction. Hypertensive patients with a nondipper circadian pattern have a greater risk of cerebrovascular and cardiovascular complications in comparison with those with a dipper circadian pattern. In this study, we evaluated the association between nondipper pattern and endothelial function in patients with essential hypertension.


METHODS
We evaluated the forearm blood flow (FBF) response to intraarterial acetylcholine (ACh), an endothelium-dependent vasodilator, and sodium nitroprusside (SNP), an endothelium-independent vasodilator, infusions in 190 hypertensive patients stratified according to dipper and nondipper status. The FBF was measured by strain-gauge plethysmography. Effects of oxidative stress on FBF were evaluated by intraarterial infusion of vitamin C. Ambulatory BP monitorings were obtained by a validated oscillometric device (SpaceLabs 90207 Monitor Inc., Issaquah, WA, USA).


RESULTS
Systolic and diastolic blood pressures were higher during daytime and lower during night-time in dipper subjects than in nondippers. The peak percent increase in ACh-stimulated FBF was higher in dippers than in nondippers (473% vs. 228%, P < 0.001). The FBF responses to SNP were similar in dipper and nondipper patients. The FBF response to ACh during coinfusion of vitamin C was higher in nondippers rather than in dipper hypertensives.


CONCLUSIONS
Present data demonstrate that endothelium-dependent vasodilation is impaired in patients who have nondipper hypertension. The effects of vitamin C on impaired ACh-stimulated vasodilation support the hypothesis that oxidative stress contributes to endothelial dysfunction of nondipper hypertensive patients.
Maio
Raffaele
R
Department of Experimental and Clinical Medicine G. Salvatore, University Magna Graecia of Catanzaro, Italy.
Perticone
Maria
M
Sciacqua
Angela
A
Tassone
Eliezer J
EJ
Naccarato
Paola
P
Bagnato
Chiara
C
Iannopollo
Gianmarco
G
Sesti
Giorgio
G
Perticone
Francesco
F
D000109:Acetylcholine / Q000502:physiology; D000328:Adult; D000368:Aged; D000704:Analysis of Variance; D000975:Antioxidants / Q000008:administration & dosage; D001205:Ascorbic Acid / Q000008:administration & dosage; D001794:Blood Pressure / Q000187:drug effects; D002940:Circadian Rhythm / Q000502:physiology; D004730:Endothelium, Vascular / Q000502:physiology*; D005260:Female; D005542:Forearm / Q000098:blood supply; D006801:Humans; D006973:Hypertension / Q000503:physiopathology*; D007275:Injections, Intravenous; D008297:Male; D008875:Middle Aged; D009599:Nitroprusside; D018384:Oxidative Stress / Q000502:physiology*; D010991:Plethysmography; D012039:Regional Blood Flow / Q000502:physiology; D014665:Vasodilator Agents; D055815:Young Adult
D000975:Antioxidants; D014665:Vasodilator Agents; D009599:Nitroprusside; D000109:Acetylcholine; D001205:Ascorbic Acid