Asymmetric distribution of purinergic and adrenergic neurotransmission cooperates in the motor activity along the rat vas deferens.

The distribution of purinergic and adrenergic responses in the epididymal and prostatic segment of the rat vas deferens were studied in vitro. Prazosin antagonizes the twitch elicited by electrical stimulation mainly in the epididymal segment while alpha,beta-methyleneadenosine 5'-triphosphate (alpha,beta-mATP) preferentially inhibits the response of the prostatic segment. Using both prazosin plus alpha,beta-mATP, the response to field stimulation was completely inhibited. Concentration-response curves revealed that adrenergic compounds elicited a greater contraction in the epididymal portion than in the prostatic end of the ductus. Purinergic compounds caused a contraction of greater magnitude in the prostatic portion. The results suggest that adrenergic and purinergic mechanisms are asymmetrically distributed along the vas deferens reflecting a gradient of adrenergic and purinergic receptors along the ductus.