A possible role of S-nitrosothiols at the nitrergic relaxations in the mouse corpus cavernosum

Relaxations induced by electrical field stimulation and acetylcholine were compared with those induced by acidified sodium nitrite, sodium nitroprussi de, S-nitrosoglutathione and S-nitroso-N-acetyl-D,L-penicillamine in the mo use corpus cavernosum precontracted with phenylephrine. N-G-nitro-L-arginin e inhibited electrical field stimulation- or acetylcholine-induced relaxati on, but was ineffective on relaxations caused by the other stimuli. Hydroqu inone and pyrogallol had no inhibitory action on the relaxations caused by any stimulus except acidified sodium nitrite. Incubation of the tissue with diethyldithiocarbamic acid significantly inhibited the relaxations induced by all stimuli except papaverine. In the tissues pre-treated with diethyld ithiocarbamic acid, superoxide dismutase, hydroquinone and pyrogallol faile d to yield restore or further inhibit the relaxations in response to electr ical field stimulation or acetylcholine. LY 83583 (6-anilino-5,8-quinolined ione) and hydroxocobalamin clearly inhibited the relaxant responses to elec trical field stimulation, acetylcholine, S-nitrosoglutathione and acidified sodium nitrite whereas there was significant enhancement of the relaxation produced by S-nitroso-N-acetyl-D,L-penicillamine. These findings suggest t hat the relaxant factor released from non-adrenergic non-cholinergic nerves or endothelial cells in mouse cavernosal tissue may be a superoxide anion- resistant nitric oxide-containing molecule and that S-nitrosoglutathione ra ther than S-nitroso-N-acetyl-D,L-penicillamine could be a suitable candidat e for this. (C) 1998 Elsevier Science B.V. All rights reserved.