Relaxant effect of ethanol on isolated rabbit corpus cavernosum and its mechanism

Objective:To study the relaxant effect of ethanol on the isolated rabbit corpus cavernosum and its possible mechanism.Methods:The tension of isolated smooth muscle strips was recorded by the plateform physiological grapher,and the concentrations of cAMP and cGMP in the rabbit corpus cavernosum were measured by 125I radioimmunoassay.Results:The 1.25 %(V/V)ethanol significantly augmented the corporal relaxation induced by isoprenaline(10-9-10-5 mol/L).Ethanol-induced relaxation was inhibited by 100 μmol/L and 300 μmol/L SQ22536(an adenylate cyclase inhibitor).Emax was depressed from(105.12±3.39) % to(97.00±2.57) % in the presence of 100 μmol/L SQ22536 or(91.09±2.42) % in the presence of 300 μmol/L SQ22536.EC50 was increased from(1.18±0.09)%(V/V) to(1.36±0.10) % in the presence of 100 μmol/L SQ22536(P0.05) or(1.68±0.13) %(in the presence of 300 μmol/L SQ22536)(P0.05)respectively.Ethanol significantly elevated the level of cAMP but not that of cGMP in the isolated rabbit corpus cavernosum,and it also significantly enhanced the activity of the adenylate cyclase(AC) extracted from the rabbit corpus cavernosum in a dose-dependent manner.Conclusion:Ethanol has a relaxant effect on the isolated rabbit corpus cavernosum,which may be associated with the cAMP signaling pathway.