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BioMed Research International
Volume 2014 (2014), Article ID 871735, 8 pages
http://dx.doi.org/10.1155/2014/871735
Research Article

GABAB Receptors Expressed in Human Aortic Endothelial Cells Mediate Intracellular Calcium Concentration Regulation and Endothelial Nitric Oxide Synthase Translocation

1The Key Laboratory of Cardiovascular Remodeling and Function Research, Chinese Ministry of Education and Chinese Ministry of Health, Qilu Hospital, Shandong University, Jinan, Shandong 250012, China
2Department of Ophthalmology, Qilu Hospital, Shandong University, Jinan, Shandong 250012, China
3School of Optometry and Vision Science, Faculty of Health, and Institute of Health and Biomedical Innovation, Queensland University of Technology, Brisbane, QLD 4059, Australia

Received 17 March 2014; Revised 5 June 2014; Accepted 23 June 2014; Published 9 July 2014

Academic Editor: Eiichi Kumamoto

Copyright © 2014 Xu-Ping Wang 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

GABAB receptors regulate the intracellular Ca2+ concentration ([Ca2+]i) in a number of cells (e.g., retina, airway epithelium and smooth muscle), but whether they are expressed in vascular endothelial cells and similarly regulate the [Ca2+]i is not known. The purpose of this study was to investigate the expression of GABAB receptors, a subclass of receptors to the inhibitory neurotransmitter γ-aminobutyric acid (GABA), in cultured human aortic endothelial cells (HAECs), and to explore if altering receptor activation modified [Ca2+]i and endothelial nitric oxide synthase (eNOS) translocation. Real-time PCR, western blots and immunofluorescence were used to determine the expression of GABAB1 and GABAB2 in cultured HAECs. The effects of GABAB receptors on [Ca2+]i in cultured HAECs were demonstrated using fluo-3. The influence of GABAB receptors on eNOS translocation was assessed by immunocytochemistry. Both GABAB1 and GABAB2 mRNA and protein were expressed in cultured HAECs, and the GABAB1 and GABAB2 proteins were colocated in the cell membrane and cytoplasm. One hundred μM baclofen caused a transient increase of [Ca2+]i and eNOS translocation in cultured HAECs, and the effects were attenuated by pretreatment with the selective GABAB receptor antagonists CGP46381 and CGP55845. GABAB receptors are expressed in HAECs and regulate the [Ca2+]i and eNOS translocation. Cultures of HAECs may be a useful in vitro model for the study of GABAB receptors and vascular biology.