Inhibition of neural ATP release by atrial natriuretic peptide in guinea-pig vas deferens

Effects of atrial natriuretic peptide (ANP) and 8-bromoguanosine 3':5'-cyclic monophosphate (8-BrcGMP) on contraction, overflow of tritium (after [H-3]noradrenaline labelling) and overflow of ATP elicited by electrical field stimulation (210 pulses/7 Hz) were studied in guinea-pig vas deferens. ANP (1-100 nM) slightly increased contractions, did not alter the overflow of tritium but decreased the overflow of ATP by up to 50%. 8-BrcGMP (3-300 mu M) markedly reduced contractions and ATP overflow with no effect on tritium overflow. Contractions were suppressed in the presence of prazosin plus suramin, and evoked overflow of ATP declined to 11%. ANP now gradually increased tritium overflow but again decreased the overflow of ATP. 8-BrcGMP did not change tritium overflow, as before, but increased ATP overflow. The results indicate that ANP inhibits neural release of ATP by a mechanism independent of guanylyl cyclase activation with no major effect on noradrenaline release.