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BioMed Research International
Volume 2014, Article ID 182846, 7 pages
http://dx.doi.org/10.1155/2014/182846
Research Article

Characterization of Imidazoline Receptors in Blood Vessels for the Development of Antihypertensive Agents

1Department of Food Science, National Pingtung University of Science and Technology, Neipu, Pingtung 91201, Taiwan
2College of Medicine and Life Science, Chung Hwa University of Medical Technology, Rende District, Tainan City 71703, Taiwan
3Department of Radiation Oncology, Taipei Medical University-Shuang Ho Hospital, and College of Medicine, Taipei Medical University, Taipei City 10361, Taiwan
4Institute of Basic Medical Sciences, College of Medicine, National Cheng Kung University, Tainan City 70101, Taiwan
5Department of Obs/Gyn, Tainan Sin-Lau Hospital, The Presbyterian Church in Taiwan, Tainan City 70142, Taiwan
6Department of Chinese Medicine, Tainan Sin-Lau Hospital, The Presbyterian Church in Taiwan, Tainan City 70142, Taiwan

Received 16 February 2014; Accepted 9 March 2014; Published 3 April 2014

Academic Editor: Juei-Tang Cheng

Copyright © 2014 Mei-Fen Chen 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

It has been indicated that activation of peripheral imidazoline I2-receptor (I-2R) may reduce the blood pressure in spontaneously hypertensive rats (SHRs). Also, guanidinium derivatives show the ability to activate imidazoline receptors. Thus, it is of special interest to characterize the I-2R using guanidinium derivatives in blood vessels for development of antihypertensive agent(s). Six guanidinium derivatives including agmatine, amiloride, aminoguanidine, allantoin, canavanine, and metformin were applied in this study. Western blot analysis was used for detecting the expression of imidazoline receptor in tissues of Wistar rats. The isometric tension of aortic rings isolated from male rats was also estimated. The expression of imidazoline receptor on rat aorta was identified. However, guanidinium derivatives for detection of aortic relaxation were not observed except agmatine and amiloride which induced a marked relaxation in isolated aortic rings precontracted with phenylephrine or KCl. Both relaxations induced by agmatine and amiloride were attenuated by glibenclamide at concentration enough to block ATP-sensitive potassium () channels. Meanwhile, only agmatine-induced relaxation was abolished by BU224, a selective antagonist of imidazoline I2-receptors. Taken together, we suggest that agmatine can induce vascular relaxation through activation of peripheral imidazoline I2-receptor to open channels. Thus, agmatine-like compound has the potential to develop as a new therapeutic agent for hypertension in the future.