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Adenosine responses in experimental vein bypass grafts
M G Davies1, V Ramkumar, P O Hagen
1Vascular Biology and Atherosclerosis Research Laboratory, Departments of Surgery and Biochemistry, Duke University Medical Center, Durham, NC, USA.
Journal of Vascular Surgery
|November 11, 1998
Summary
Vein grafts exhibit unique adenosine responses, with A1 receptor activation causing contraction and A2 receptor signaling preserving nitric oxide-mediated relaxation, unlike native veins or arteries.
Area of Science:
- Vascular biology
- Pharmacology
- Cardiovascular research
Background:
- Vein grafts undergo phenotypic changes in arterial circulation.
- Receptor-mediated relaxation is often impaired in vein grafts.
- Adenosine is a potent endogenous vasodilator with potential therapeutic applications.
Purpose of the Study:
- To investigate vein graft responses to adenosine.
- To compare these responses with native veins and arteries.
- To elucidate the role of adenosine receptors (A1 and A2) in vein graft function.
Main Methods:
- Assessed adenosine receptor presence (A1, A2) using radioligand binding.
- Evaluated in vitro responses to adenosine analogues in rabbit carotid jugular vein grafts.
- Determined the contribution of nitric oxide (NO) and prostanoids to relaxation.
- Studied both endothelialized and de-endothelialized vessels.
Main Results:
- Vein graft adenosine responses differ from jugular veins and carotid arteries.
- Adenosine-mediated relaxation in vein grafts is NO and prostanoid dependent.
- A1 receptor activation induced endothelium-dependent contraction in vein grafts.
- A2 receptor-mediated responses were endothelium-independent in vein grafts.
- Vein grafts showed an A1/A2 receptor ratio closer to native veins.
Conclusions:
- Vein graft adenosine responses are unique, not fully venous or arterial.
- Endothelial A1 receptor-mediated responses shift from relaxation to contraction.
- A2 receptor signaling likely preserves NO-mediated relaxation in vein grafts.