Endothelial and neuronal-derived nitric oxide mediated relaxation of corpus cavernosal smooth muscle in a rat, in vitro, model of erectile function

We set out to establish a simple, reproducible, rat in vitro model of erect ile function and to use this to demonstrate the functional importance of bo th neuronal- and endothelial-derived nitric oxide within this animal. Two corpora cavernosal smooth muscle strips were harvested from sexually ma ture male Wistar rats and mounted in an organ bath for measurement of isome tric tension, Following contraction with noradrenaline the strips were rela xed by the addition of either acetylcholine or sodium nitroprusside. Electr ical field stimulation was performed in the presence of atropine and guanet hidine. Relaxation responses were repeated in the presence of methylene blu e, L-arginine, L-NNA and haemoglobin +/- L-arginine, Methylene blue abolishes the relaxation to acetylcholine and EFS; L-NNA and haemoglobin cause a significant impairment in the relaxation response, L-a rginine reverses the effect of haemoglobin. In conclusion, the inhibitory, relaxant stimulus of rat corpora cavernosa i s due to both neuronal nitric oxide and endothelial-derived nitric oxide re leased in response to cholinergic stimulation.