Neurotransmitters adenosine triphosphate and noradrenaline induce nitric oxide release in rat vas deferens

1 In rat vas deferens, electrical held stimulation (EFS) evoked a muscular biphasic tetrodotoxin (TTX)-sensitive contractile response. 2 The amplitude of this response increased with the frequency of stimulatio n. 3 After each stimulation, nitric oxide (NO) release was assayed and found t o be released in a frequency-dependent manner. 4 NO release also occurred after treatment with exogenous neurotransmitters , adenosine 5'-triphosphate (ATP) and noradrenaline (NA). 5 Prazosin and pyridoxalphosphate-6-azophenyl-2',4'-disulphonic acid (PPADS ), respective antagonists of alpha (1)-adrenoceptors and P-2x purinoceptors , inhibited NO release induced by NA and ATP. Both prazosin and PPADS inhib ited NO release by EFS. 6 TTX failed to modify the NO release induced by exogenous neurotransmitter s but abolished the release of NO and contractile response by EFS. 7 EFS and released noradrenaline and ATP induce the release of NO through p ostjunctional alpha (1)-adrenoceptors and P-2x-purinoceptors, respectively.