Adenosine is an endogenous nucleoside that has potent antiarrhythmic effects on paroxysmal supraventricular tachycardia (PSVT) due to its negative dromotropic effects on the atrioventricular node. In addition to its electrophysiologic effects, adenosine has important effects on vascular smooth muscle cells, inflammatory cells, the central nervous system, and the kidney. Activation of the A1 adenosine receptor accounts for the negative chronotropic and dromotropic effects of adenosine, whereas A2A, A2B and A3 adenosine receptor activation are responsible for such effects as coronary vasodilation, bronchospasm, inhibition of platelet aggregation, and neuronal stimulation[1].Tecadenoson (CVT-510) is a selective A1 adenosine receptor agonist. In the atrial-paced isolated heart, Tecadenoson is approximately 5 fold more potent to prolong the stimulus-to-His bundle (S-H interval), a measure of slowing AV nodal conduction (EC50=41 nM) than to increase coronary conductance (EC50=200 nM). At concentrations of Tecadenoson (40 nM) and diltiazem (1 μM) that causes equal prolongation of S-H interval (∼10 ms), diltiazem, but not Tecadenoson, significantly reduces left ventricular developed pressure (LVP) and markedly increases coronary conductance. Tecadenoson shortens atrial (EC50=73 nM) but not the ventricular monophasic action potentials (MAP)[2]. In atrial-paced anaesthetized guinea-pigs, intravenous infusions of Tecadenoson and diltiazem causes nearly equal prolongations of P-R interval. Tecadenoson (2, 5, 20 μg/kg i.p.) causes a rapid and sustained dose-dependent decrease in NEFA at doses that do not cause bradycardia. Tecadenoson given at 50 μg/kg causes a significant bradycardia (50% decrease in heart rate at 25 min[3]. Pretreatment of mice with a phosphorylated prodrug of nitrobenzylmercaptopurine riboside, an inhibitor of mENT1, significantly decreased brain exposure to tecadenoson compared with that of the untreated (control) group, suggesting involvement of mENT1 in transport of tecadenoson across the blood-brain barrier (BBB){{ Eve-Irene Lepist,et al. Transport of A1 adenosine receptor agonist tecadenoson by human and mouse nucleoside transporters: evidence for blood-brain barrier transport by murine equilibrative nucleoside transporter 1 mENT1. Drug Metab Dispos
. 2013 Apr;41(4):916-22.| https://pubmed.ncbi.nlm.nih.gov/23388705/}}.
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