Cardiovascular biology of the A3 adenosine receptor

Abstract

The goal of this chapter is to review current theories regarding the potential involvement of the A3 receptor in mediating the actions of adenosine in the cardiovascular system. The Gi protein-coupled A3 adenosine receptor is the last adenosine receptor subtype to be discovered and remains poorly characterized in terms of its molecular biology and biological functions (Linden 1994). Recent evidence suggests that the A3 receptor may mediate the actions of adenosine to regulate vascular tone and angiogenesis, either directly or indirectly by stimulating the release of mediators from mast cells. Substantial evidence has accumulated to suggest that the A3 receptor is responsible for some of the beneficial effects of adenosine in reducing injury caused by ischemia and reperfusion. Readers are reminded that the A3 receptor has proven to be the most difficult adenosine receptor subtype to research due to its unique pharmacological properties and unusual species differences in terms of its pharmacology, tissue expression, and biological function (Linden 1994). The theories described in this chapter remain controversial and require additional verification as new tools become available to study this fascinating member of the adenosine receptor family.