Circadian variation of blood pressure and endothelial function in patients with essential hypertension:a comparison of dippers and non-dippers.
OBJECTIVE
The purpose of this study was to evaluate the relationship between the circadian blood pressure (BP) rhythm and endothelial function in patients with essential hypertension.


BACKGROUND
Hypertension is associated with alterations in resistance artery endothelial function. Patients with a non-dipper circadian pattern of BP have a greater risk of cerebrovascular and cardiovascular complications than do patients with a dipper circadian pattern.


METHODS
We evaluated the forearm blood flow (FBF) response to intra-arterial acetylcholine (ACh), an endothelium-dependent vasodilator, and isosorbide dinitrate (ISDN), an endothelium-independent vasodilator, infusion in 20 patients with non-dipper hypertension and 20 age- and gender-matched patients with dipper hypertension. The FBF was measured using a mercury-filled Silastic strain-gauge plethysmograph.


RESULTS
The 24-h systolic BP, as well as nocturnal systolic and diastolic BPs were higher in non-dipper patients than in dipper patients. The 24-h urinary excretion of nitrite/nitrate and cyclic guanosine monophosphate was lower in non-dippers than in dippers. The response of FBF to ACh was smaller in non-dippers than in dippers (25.1 +/- 3.1 vs. 20.2 +/- 3.0 ml/min/100 ml tissue, p < 0.05). The FBF response to ISDN was similar in dippers and non-dippers. The FBF response to ACh was similar in the two groups following intra-arterial infusion of the nitric oxide (NO) synthase inhibitor N(G)-monomethyl-L-arginine.


CONCLUSIONS
These findings suggest that endothelium-dependent vasodilation is blunted through a decrease in NO release in non-dippers compared with patients who have dipper hypertension.
Higashi
Yukihito
Y
Department of Cardiovascular Physiology and Medicine, Graduate School of Biomedical Sciences, Hiroshima University, Japan. yhigashi@hiroshima-u.ac.jp
Nakagawa
Keigo
K
Kimura
Masashi
M
Noma
Kensuke
K
Hara
Keiko
K
Sasaki
Satoshi
S
Goto
Chikara
C
Oshima
Tetsuya
T
Chayama
Kazuaki
K
Yoshizumi
Masao
M
D000109:Acetylcholine / Q000008:administration & dosage; D000328:Adult; D001783:Blood Flow Velocity / Q000187:drug effects / Q000502:physiology; D001794:Blood Pressure / Q000187:drug effects / Q000502:physiology*; D002940:Circadian Rhythm / Q000187:drug effects / Q000502:physiology*; D006152:Cyclic GMP / Q000652:urine; D003971:Diastole / Q000187:drug effects / Q000502:physiology; D004305:Dose-Response Relationship, Drug; D004730:Endothelium, Vascular / Q000187:drug effects / Q000502:physiology*; D005260:Female; D005542:Forearm / Q000098:blood supply; D006339:Heart Rate / Q000187:drug effects / Q000502:physiology; D006801:Humans; D006973:Hypertension / Q000503:physiopathology*; D007261:Infusions, Intra-Arterial; D007564:Japan / Q000453:epidemiology; D008297:Male; D008875:Middle Aged; D009569:Nitric Oxide / Q000652:urine; D019001:Nitric Oxide Synthase / Q000037:antagonists & inhibitors; D015588:Observer Variation; D013599:Systole / Q000187:drug effects / Q000502:physiology; D014665:Vasodilator Agents / Q000008:administration & dosage; D019323:omega-N-Methylarginine / Q000008:administration & dosage
D014665:Vasodilator Agents; D019323:omega-N-Methylarginine; D009569:Nitric Oxide; D019001:Nitric Oxide Synthase; D006152:Cyclic GMP; D000109:Acetylcholine