Evidence that Adrenergic and Cholinergic but Not Capsaicin-Sensitive Nerves Are Involved in the Nerve-Mediated Contraction of the Guinea Pig Seminal Vesicle

Background/Aims: The neurotransmitters participating in the nerve-mediated contraction of the guinea pig seminal vesicle (GPSV) have not been firmly established. There is debate as to the mediating role of norepinephrine and acetylcholine. Methods: We have used longitudinally and circularly oriented strips of GPSV and activated their intramural nerves by electrical field stimulation (5 and 10 Hz for 30 s). Results: Contractile responses to stimulation were enhanced by a cholinesterase inhibitor and reduced by the adrenergic α-receptor antagonist phentolamine (2.5 μmol/l). Atropine (1 μmol/l) significantly reduced responses in longitudinal preparations; a less consistent inhibition was found in circular preparations. The sensory neuron stimulant and blocker capsaicin was without effect. Conclusions: It is concluded that adrenergic nerves and also acetylcholine mediate the contractile response of the GPSV.