sodium-nitrite and hydroquinone

Relaxations induced by electrical field stimulation and acetylcholine were compared with those induced by acidified sodium nitrite, sodium nitroprusside, S-nitrosoglutathione and S-nitroso-N-acetyl-D,L-penicillamine in the mouse corpus cavernosum precontracted with phenylephrine. NG-nitro-L-arginine inhibited electrical field stimulation- or acetylcholine-induced relaxation, but was ineffective on relaxations caused by the other stimuli. Hydroquinone 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 diethyldithiocarbamic acid, superoxide dismutase, hydroquinone and pyrogallol failed to yield restore or further inhibit the relaxations in response to electrical field stimulation or acetylcholine. LY 83583 (6-anilino-5,8-quinolinedione) and hydroxocobalamin clearly inhibited the relaxant responses to electrical 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 that 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 rather than S-nitroso-N-acetyl-D,L-penicillamine could be a suitable candidate for this.

Topics: Acetylcholine; Aminoquinolines; Animals; Chelating Agents; Ditiocarb; Electric Stimulation; Enzyme Inhibitors; Hematinics; Hydrogen-Ion Concentration; Hydroquinones; Hydroxocobalamin; In Vitro Techniques; Male; Mercaptoethanol; Mice; Muscle Relaxation; Muscle, Smooth; Mutagens; Nitric Oxide; Nitroarginine; Nitroprusside; Nitroso Compounds; Penis; Pyrogallol; S-Nitrosothiols; Sodium Nitrite; Vasodilator Agents

The relaxant effects of electrical field stimulation (EFS) and exogenously applied acetylcholine (ACh) or acidified NaNO2 (a-NaNO2) were investigated in the isolated mouse corpus cavernosum precontracted with phenylephrine hydrochloride (PE). Tetrodotoxin (TTX) blocked the relaxant effects of EFS completely, whereas it had no effect on the responses to ACh or a-NaNO2. Guanethidine and indomethacin failed to affect the electrically or ACh-induced relaxations. Atropine completely blocked the effect of ACh; however, it caused a slight reduction in the relaxation evoked by EFS. NG-Nitro-L-arginine (L-NOARG) reduced the effects of EFS and ACh significantly, but it was ineffective on the relaxations induced by a-NaNO2. The inhibitory action of L-NOARG was partly restored by L-arginine, but not by D-arginine. Methylene blue (MB) and hydroxocobalamin (HC) exhibited significant inhibition on the relaxations evoked by EFS, ACh and a-NaNO2. Hydroquinone (HQ) reduced relaxation due to a-NaNO2, but did not affect that of EFS and ACh. Our findings suggest that EFS-induced relaxations of mouse cavernosal tissue are mediated by a transmitter which probably resembles an organic nitrate.

Topics: Acetylcholine; Adrenergic Agents; Adrenergic alpha-Agonists; Animals; Antidotes; Arginine; Cyclooxygenase Inhibitors; Electric Stimulation; Electrophysiology; Enzyme Inhibitors; Guanethidine; Hematinics; Hydroquinones; Hydroxocobalamin; Indomethacin; Male; Methylene Blue; Mice; Mice, Inbred Strains; Mutagens; Nitroarginine; Penile Erection; Penis; Phenylephrine; Sodium Nitrite; Tetrodotoxin