Investigation of nitrergic relaxations of corpus cavernosum smooth muscle in chronic ethanol-dependent mice

ABSTRACTInvestigation of Nitrergic Relaxations of Corpus Cavernosum Smooth Muscle inChronic Ethanol-Dependent MiceThe effect of chronic ethanol intake on nitrergic relaxations was investigated inthe corpus cavernosum isolated from chronically ethanol inhalated mice for 7 and 14days. Corpus cavernosum from control mice and the mice exposed to chronic alcoholvapour were mounted under a load of 200 mg in tissue baths (15 ml) containing Krebssolution, maintained 370C , %95 O2 and %5 CO2 gassed. Tissues were contracted with,phenylephrine (5x10-6 M), an 1-receptor agonist. When a stable contraction wasobtained, consecutive electrically filed stimulation (EFS; 8 Hz, 30 V, 0.5 msn, 15 sn),exogenous nitric oxide (NO; 10-4 M) and acetylcholine (10-7 M) relaxations induced.There was no significantly difference in relaxations between the 7 days-ethanolinhalated mice and control mice. However, acetylcholine-induced relaxation wassignificantly decreased in the 14 days-ethanol inhalated mice. L-nitroarginine (10-4 M),NOS synthase inhibitor, significantly reduced EFS and acetylcholine-inducedrelaxations but not those to exogenous NO in both control mice and 14 days-ethanolinhalated mice. Addition of L-arginine (10-4 M) reversed this inhibitory effect of L-nitroarginine on EFS and acetylcholine-induced relaxations. Also, ODQ (10-4 M),guanylate cyclase inhibitor, inhibited EFS, NO and acetylcholine-induced relaxations inboth control mice and 14 days-ethanol inhalated mice. Furthermore, corpus cavernosumtissues were investigated under electron microscopy. Endothelium damage wasobserved in 14 days-ethanol inhalated mice, however, there was no ultrastructuralchange in the control mice.In conclusion, acetylcholine-induced relaxation significantly reduced in corpuscavernosum tissue from 14 days-ethanol inhalated mice, whereas there was nodifference between ESS and NO-induced relaxations, and it was determinedendothelium damage in ethanol-inhalated mice, suggesting that chronic ethanol maylead to erectile dysfunction through a decreasing NO release from endothelium via anendothelial impairment.Key words: Mice, corpus cavernosum, chronic ethanol, nitrergic relaxation, nitric oxide