Relationship between arterial and venous adenosine levels and vasodilatation during ATP‐and adenosine‐infusion in dogs

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Abstract
The hemodynamic effects of ATP and adenosine (i.v.) were studied in dogs in parallel with quantitative determination of purines in plasma by HPLC [high performance liquid chromatography]. In 2 experiments, infusion was performed during treatment with dipyridamole, an uptake inhibitor of adenosine. A 50-60% reduction of mean arterial blood pressure (MABP) was induced by both ATP and adenosine infusion rates ranging between 17-290 .mu.mol/min. Cardiac output was unaffected by the purine infusions, indicating that the reduction of MABP was caused by a reduction of the systemic vascular resistance. Elevated ATP and adenosine concentrations were seen in venous plasma (pulmonary artery) during infusion, while only approximately 10% recovered ATP had been degraded to adenosine. In arterial plasma, virtually all nucleotides had been eliminated whereas the adenosine concentrations in plasma ranged between 5 and 20 .mu.M. The magnitude of the vasodilatation was strictly related to the arterial plasma adenosine level irrespective of whether ATP or adenosine was infused. Adenosine probably mediates the vasodilatory effect of ATP.