title: Autonomic nervous activation triggered during induction of reactive hyperemia exerts a greater influence on the measured reactive hyperemia index by peripheral arterial tonometry than on flow-mediated vasodilatation of the brachial artery in patients with hypertension.
abstract: Flow-mediated vasodilatation of the brachial artery (FMD) and reactive hyperemia index (RHI) measured by peripheral arterial tonometry are known to be weakly associated with one another, but the mechanisms underlying this weak association remain to be clarified. We examined whether the autonomic nervous activation induced by the 5 min forearm clamping used to induce reactive hyperemia might exert any influence on the FMD and RHI in subjects with hypertension. In 115 subjects with hypertension (age 61±1 years), the FMD and RHI were measured simultaneously, and the heart rate variability (HRV) parameters (low-frequency component (LF), high-frequency component (HF), and the ratio (LF/HF) between the two) were calculated from the electrocardiographic recordings obtained before and after the start of forearm clamping. A multivariate linear regression analysis with adjustments for confounding variables demonstrated that the RHI, but not the FMD, was significantly associated with the percent change of the LF/HF associated with forearm clamping (beta=-0.204, P=0.043). In conclusion, autonomic nervous system activation, especially sympathetic activation, induced by 5-min forearm clamping utilized to provoke reactive hyperemia may significantly affect the RHI rather than FMD in subjects with hypertension.
authors.affiliation: Second Department of Internal Medicine, Tokyo Medical University, Tokyo, Japan.
authors.forename: Hirofumi
authors.initials: H
authors.lastname: Tomiyama
authors.affiliation: Second Department of Internal Medicine, Tokyo Medical University, Tokyo, Japan.
authors.forename: Masanobu
authors.initials: M
authors.lastname: Yoshida
authors.affiliation: Department of Cardiovascular Physiology and Medicine, Hiroshima University Graduate School of Biomedical Science, Hiroshima, Japan.
authors.forename: Yukihito
authors.initials: Y
authors.lastname: Higashi
authors.affiliation: Division of Biomedical Engineering, National Defense Medical College Research Institute, Saitama, Japan.
authors.forename: Bonpei
authors.initials: B
authors.lastname: Takase
authors.affiliation: Department of Cardiovascular Medicine, Hokkaido University Graduate School of Medicine, Hokkaido, Japan.
authors.forename: Tomoo
authors.initials: T
authors.lastname: Furumoto
authors.affiliation: Division of Cardiovascular Medicine, Jichi Medical University School of Medicine, Tochigi, Japan.
authors.forename: Kazuomi
authors.initials: K
authors.lastname: Kario
authors.affiliation: Third Department of Internal Medicine, University of the Ryukyus, Okinawa, Japan.
authors.forename: Yusuke
authors.initials: Y
authors.lastname: Ohya
authors.affiliation: Second Department of Internal Medicine, Tokyo Medical University, Tokyo, Japan.
authors.forename: Akira
authors.initials: A
authors.lastname: Yamashina
mesh_terms: D000368:Aged; D001158:Arteries / Q000503:physiopathology*; D001341:Autonomic Nervous System / Q000503:physiopathology*; D001916:Brachial Artery / Q000503:physiopathology*; D004730:Endothelium, Vascular / Q000503:physiopathology; D005260:Female; D005542:Forearm / Q000098:blood supply; D006339:Heart Rate; D006801:Humans; D006940:Hyperemia / Q000503:physiopathology*; D006973:Hypertension / Q000503:physiopathology*; D008297:Male; D008365:Manometry; D008875:Middle Aged; D012039:Regional Blood Flow; D014664:Vasodilation