, Volume 105, Issue 1, pp 1-5
Date: 26 Nov 2009

Adenosine and maximum coronary vasodilation in humans: myth and misconceptions in the assessment of coronary reserve

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In the heart, the purine nucleoside adenosine acts on heart rate, contractile function and coronary blood flow. Adenosine acts as a negative chronotrope in the sinoatrial and atrioventricular nodes and in atrial myocytes through adenosine A1 receptor activation [43, 45]. Adenosine acts as a negative inotrope, largely through its anti-adrenergic action after adenosine A1 receptor activation [43]. Adenosine acts as a coronary dilator, largely through activation of adenosine A2A receptors [43, 45]. In humans, arteriolar dilation in response to adenosine is mediated by A2A receptors, adenylate cyclase and calcium-activated potassium channels in vascular smooth muscle cells [52]. Also, indirect effects contribute to the role of adenosine in coronary blood flow: adenosine inhibits presynaptic release of norepinephrine from sympathetic nerves [43], inhibits platelet aggregation [35] and inhibits leukocyte adherence to the vascular wall [59]. A1 receptors are coupled to Gi/o proteins and their ...