The goal of this application is to elucidate the mechanisms of adenosine receptor (AR) signaling in the control of coronary vascular tone (CVT). There is a critical need to fully understand the control of CVT by adenosine (Ad) in normal and diseased hearts. We have achieved the major goals of the last renewal and made tremendous progress on how Ad interacts with the coronary artery (CA) smooth muscle cells (SMC) and endothelium (E) to produce relaxation using the single AR KO's (except A2B). We have shown that CASMC and E contain both A2A and A2B relaxing ARs;and CASMC and E also contain A1 and A3 contracting ARs. We established a major role for A2A and a minor role for A2B in the relaxation of CA and the involvement of A1 and A3 in the contraction of CA. Also, we established that E plays a role in releasing mediators (NO and COX-I products) that play opposite roles in modulating the action of Ad through 4 ARs. A1 AR in CASMC involves activation of PLC-2III->PKC1 ->p42/44 in causing contraction. A2B causes relaxation thorough p-38 MAPK. However, we have observed an up-regulation of A2B in A2A and vice versa in single KO's. Thus, in order to avoid the compensatory phenotypic response of other ARs, we have created the double KO (DKO's, A2A/A2B and A1/A3) for functional and signaling experiments for this project. Our central hypothesis is that the control of CVT by Ad is determined by a net effect of relaxing (A2A/B, including E factors) and contracting (A1/3, including E factors) ARs. Binding of Ad to ARs may initiate signaling (Fig. A) through G proteins resulting in activation of distinct pathways to control CVT. This novel hypothesis will be tested with the use of innovative physiological genomic approaches using single and DKOs (A1/A3 and A2A/A2B). Use of DKO allows precise examination of AR-mediated signaling without the compensatory responses than through traditional approaches. Therefore, using single and DKO's, we propose 3 aims with isolated hearts, CASMC (+E cells) and aorta/mesenteric artery :(a) to characterize the relaxing and contracting phenotypic effects of Ad agonists/antagonists;(b) to identify the signaling involved in the action of Ad in coronary endothelial cells (release of NO from A2A andA2B (and A2A/A2B) and the coupling of A1 and A3 (and A1/A3) to PLA2;and the signaling in CASMC in A2A, A2B and A2A/A2B (PKA-p38-MAPK-HSP20) and in A1, A3 and A1/ A3 (PLC2III, PKC1, AKT and p42/44 ERK);and finally, (c) to investigate the roles of A1 andA3 in producing and the roles of A2A and A2B in inhibiting oxidative stress, respectively in the action of Ad. These studies have never been proposed before and, thus, the characterization of the heterogeneity of ARs and their signaling in the control of CVT by Ad using DKO are innovative and will move the field forward in two ways;(a) will have a positive impact in the field of vascular biology, in general, (b) will have a positive impact in the field of AR signaling, in particular. These studies will lead to the development of novel therapeutic agents for vascular disorders. Finally, our past work was instrumental in the approval of an A2A AR selective agonist (Lexican(R)) for myocardial perfusion imaging.

Public Health Relevance

Adenosine plays an important role in the regulation of blood flow to the heart. There is a critical need to better understand the blood flow to the heart by adenosine in normal and diseased hearts. This proposal is directed towards the understanding of the involvement of all four adenosine receptor (s) in blood flow regulation to the heart. This project will utilize all four single and double AR gene deleted mice to understand the signaling pathways for each AR subtype.

National Institute of Health (NIH)
National Heart, Lung, and Blood Institute (NHLBI)
Research Project (R01)
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Vascular Cell and Molecular Biology Study Section (VCMB)
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Keleti, Julianna
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West Virginia University
Schools of Medicine
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Labazi, Hicham; Teng, Bunyen; Mustafa, S Jamal (2018) Functional changes in vascular reactivity to adenosine receptor activation in type I diabetic mice. Eur J Pharmacol 820:191-197
Zhou, Zhichao; Yadav, Vishal R; Sun, Changyan et al. (2017) Impaired Aortic Contractility to Uridine Adenosine Tetraphosphate in Angiotensin II-Induced Hypertensive Mice: Receptor Desensitization? Am J Hypertens 30:304-312
Teng, Bunyen; Labazi, Hicham; Sun, Changyan et al. (2017) Divergent coronary flow responses to uridine adenosine tetraphosphate in atherosclerotic ApoE knockout mice. Purinergic Signal 13:591-600
Ashton, Kevin J; Reichelt, Melissa E; Mustafa, S Jamal et al. (2017) Transcriptomic effects of adenosine 2A receptor deletion in healthy and endotoxemic murine myocardium. Purinergic Signal 13:27-49
Teng, Bunyen; Tilley, Stephen L; Ledent, Catherine et al. (2016) In vivo assessment of coronary flow and cardiac function after bolus adenosine injection in adenosine receptor knockout mice. Physiol Rep 4:
Labazi, Hicham; Tilley, Stephen L; Ledent, Catherine et al. (2016) Role of Adenosine Receptor(s) in the Control of Vascular Tone in the Mouse Pudendal Artery. J Pharmacol Exp Ther 356:673-80
Labazi, Hicham; Teng, Bunyen; Zhou, Zhichao et al. (2016) Enhanced A2A adenosine receptor-mediated increase in coronary flow in type I diabetic mice. J Mol Cell Cardiol 90:30-7
Zhou, Xueping; Teng, Bunyen; Mustafa, S J (2015) Sex Difference in Coronary Endothelial Dysfunction in Apolipoprotein E Knockout Mouse: Role of NO and A2A Adenosine Receptor. Microcirculation 22:518-27
Zhou, Zhichao; Rajamani, Uthra; Labazi, Hicham et al. (2015) Involvement of NADPH oxidase in A2A adenosine receptor-mediated increase in coronary flow in isolated mouse hearts. Purinergic Signal 11:263-73
Zhou, Zhichao; Sun, Changyan; Tilley, Stephen L et al. (2015) Mechanisms underlying uridine adenosine tetraphosphate-induced vascular contraction in mouse aorta: Role of thromboxane and purinergic receptors. Vascul Pharmacol 73:78-85

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