Introduction: The vasoconstrictor effect of noradrenaline is influenced by many neurohumoral agents. We investigated if the endothelial ATP has such an effect on the release of noradrenaline. Materials and Methods: We measured the release of tritiated noradrenaline after electrical field stimulation. The difference between the four experimental groups was that in two groups we removed the endothelium and in two groups we used the selective purinoreceptor blocker, Reactive Blue 2. Results: The results in all the four groups were broadly the same, the differnces were not statisticly significant. Conclusion: The endothelial ATP did’t show the presumed neuromodulator effect on noradrenaline release.