Origin of ATP release in the rat vas deferens: concomitant measurement of [3H]noradrenaline and [14C]ATP.

High pressure liquid chromatography (HPLC) combined with radiochemical detection was used to show that [3H]noradrenaline (NA) and [14C]ATP were released concomitantly during field stimulation of the rat vas deferens. The release of radioactivity (3H and 14C) in response to three consecutive field stimulations was constant (S2/S1 and S3/S2: 0.89 +/- 0.10 and 0.91 +/- 0.04 for 3H and 1.03 +/- 0.12 and 1.08 +/- 0.07 for 14C, respectively) and Ca2+-dependent. Tetrodotoxin completely inhibited the release of both NA and ATP. However, the alpha 1-antagonist, prazosin, enhanced the release of [3H]NA, and significantly reduced that of [14C]ATP. Exogenously applied NA produced an increase in ATP release which was antagonized by prazosin. 4-Aminopyridine substantially enhanced the release of ATP in the presence of prazosin, clearly indicating that some ATP originates from nerves. It is concluded that part of the ATP collected during stimulation of the rat vas deferens was released from nerves together with NA. In addition, a significant amount of ATP was released secondarily as a result of NA action via alpha 1-adrenoceptors. The experiments provide no information about whether the prazosin-sensitive component of release of ATP originates from smooth muscle or from axon terminals.