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Experimental Diabetes Research
Volume 2011 (2011), Article ID 489708, 7 pages
Research Article

Assessment of Glucagon-Like Peptide-1 Analogue and Renin Inhibitor on the Binding and Regulation of GLP-1 Receptor in Type 1 Diabetic Rat Hearts

1Department of Physiology, Faculty of Medicine, American University of Beirut, Beirut 11-236, Lebanon
2Department of Physics, Faculty of Arts and Sciences, American University of Beirut, Beirut 11-236, Lebanon

Received 8 December 2010; Revised 11 February 2011; Accepted 21 March 2011

Academic Editor: Giovanni Di Pasquale

Copyright © 2011 Shushan B. Artinian 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.


This study focuses on the effects of long-term renin-angiotensin system suppression and/or incretin mimetic therapies on the regulation and binding affinity of GLP-1 to its receptor in the coronary endothelium (CE) and cardiomyocytes (CMs) of type 1 diabetic male Sprague-Dawley rats. The groups assessed are normal (N), streptozotocin-induced diabetic (D), Insulin treated (DI), Exendin-4 treated (DE), Aliskiren treated (DA), cotreated with Insulin and Aliskiren (DIA) and cotreated with exendin-4 and Aliskiren (DEA). Heart perfusion with 125I-GLP-1 was performed to estimate GLP-1 binding affinity ( 𝜏 = 1 / 𝑘 𝑛 ) to its receptor in the heart. Western Blotting was assessed to determine the expression variation of GLP-1 receptor in the heart. Plasma GLP-1 levels were measured using Enzyme-Linked Immunosorbent Assay (ELISA). Diabetes decreased the 𝜏 value on CE and increased it on CMs compared to normal. The combination of Exendin-4 with Aliskiren showed a normalizing effect on the binding affinity of GLP-1 at the coronary endothelium, while at the cardiomyocyte level Exendin-4 treatment alone was the most effective.