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International Journal of Hypertension
Volume 2015 (2015), Article ID 759629, 7 pages
http://dx.doi.org/10.1155/2015/759629
Research Article

Brain Angiotensin II Type 1 Receptor Blockade Improves Dairy Blood Pressure Variability via Sympathoinhibition in Hypertensive Rats

1Department of Advanced Therapeutics for Cardiovascular Diseases, Kyushu University Graduate School of Medical Sciences, 3-1-1 Maidashi, Higashi-ku, Fukuoka 812-8582, Japan
2Department of Advanced Cardiovascular Regulation and Therapeutics, Kyushu University Graduate School of Medical Sciences, 3-1-1 Maidashi, Higashi-ku, Fukuoka 812-8582, Japan
3Department of Cardiovascular Medicine, Kyushu University Graduate School of Medical Sciences, 3-1-1 Maidashi, Higashi-ku, Fukuoka 812-8582, Japan

Received 19 September 2014; Revised 15 December 2014; Accepted 15 December 2014

Academic Editor: Jiguang Wang

Copyright © 2015 Takuya Kishi et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Abstract

Abnormal blood pressure (BP) elevation in early morning is known to cause cardiovascular events. Previous studies have suggested that one of the reasons in abnormal dairy BP variability is sympathoexcitation. We have demonstrated that brain angiotensin II type 1 receptor (AT1R) causes sympathoexcitation. The aim of the present study was to investigate whether central AT1R blockade attenuates the excess BP elevation in rest-to-active phase in hypertensive rats or not. Stroke-prone spontaneously hypertensive rats (SHRSP) were treated with intracerebroventricular infusion (ICV) of AT1R receptor blocker (ARB), oral administration of hydralazine (HYD), or ICV of vehicle (VEH). Telemetric averaged mean BP (MBP) was measured at early morning (EM), after morning (AM), and night (NT). At EM, MBP was significantly lower in ARB to a greater extent than in HYD compared to VEH, though MBP at AM was the same in ARB and HYD. At NT, MBP was also significantly lower in ARB than in HYD. These results in MBP were compatible to those in sympathoexcitation and suggest that central AT1R blockade attenuates excess BP elevation in early active phase and continuous BP elevation during rest phase independent of depressor response in hypertensive rats.