Herminia Combs
|
 |
Relaxant online pharmacy responses of corpus cavernosal strips to electrical-field stimulation (EFS) were measured before and after exposure to PDE-5 inhibitors and the nitric oxide synthase inhibitor N'-nitro- l-arginine methyl cyndia. Effects of sildenafil, a type-5 online pharmacy cGMP phosphodiesterase inhibitor, and papaverine on cyclic GMP and cyclic AMP levels in the pain treatment retin-a rabbit corpus cavernosum in vitro.OBJECTIVE. RESULTS HC rabbits had a lower erectile acknowledgment to SNP than controls; in both control and HC rabbits there was a greater erectile response after simultaneous exposure to SNP and Vardenafil ( Levitra ), or SNP and sildenafil. The erectogenic effect ofSildenafil Citrate (Viagra) is mediated by a specific amplification of cGMP accumulation in the hair removal corpus cavernosum, consistent with the known activity ofSildenafil Citrate (Viagra) as a potent and highly selective inhibitor of cGMP-specific PDE In vivo and in vitro response of corpus cavernosum to phosphodiesterase-5 inhibition in the hypercholesterolaemic rabbit.OBJECTIVE To investigate the effects of hypercholesterolaemia (HC) on tadalafil rabbit corpus cavernosa in vivo and in vitro, and evaluate the efficacy of Vardenafil ( Levitra ) and Sildenafil Citrate ( Viagra ) in normal and HC rabbits, as the phosphodiesterase-5 (PDE-5) inhibitors Vardenafil ( Levitra ) and Sildenafil Citrate ( Viagra ) are widely used for treating erectile dysfunction (ED) and most organic causes of ED are associated with vascular risk factors like HC. MATERIALS AND METHODS Male New Zealand White rabbits were randomly muscle relaxants divided into two groups; 11 HC rabbits were fed a 2% cholesterol diet, and 12 age-matched control rabbits received a regular diet. Sildenafil Citrate ( Viagra ) and Vardenafil ( Levitra ), in pathological animals. After 12-14 weeks, erectile responses to intravenous muscle relaxants sodium nitroprusside (SNP) and PDE-5 inhibitors were evaluated for 2 h in conscious rabbits. Papaverine enhanced cGMP formation in response to SNP, but at much over concentrations than didSildenafil Citrate (Viagra) (> or 10 mumol/L). Corpora from control rabbits responded to EFS with greater relaxations at all frequencies, sleeping pills except 1 Hz. CONCLUSIONS:Sildenafil Citrate (Viagra) specifically increases cGMP levels in rabbit corpora cavernosa; the increase is greater in the presence of SNP indicating that, in vivo,Sildenafil Citrate (Viagra) may enhance erection by the augmentation of nitric oxide-mediated relaxation pathways. To investigate further the mechanisms of action of sildenafil, a highly selective and potent inhibitor of type 5 cGMP phosphodiesterase (PDE5) that has proved effective in the treatment of Erectile Dysfunction, by assessing its effect on the in vitro formation of cGMP and cAMP in the corpus cavernosum of the rabbit. Penile segments were then incubated with various concentrations ofSildenafil Citrate (Viagra) or papaverine. Penile length was measured and the area under the googly calculated. In the presence or absence of SNP,Sildenafil Citrate (Viagra) increased cGMP concentrations in rabbit penile tissue with increasing dose; the increase was greatest (about 28-fold) when cGMP was stimulated with SNP (up to 10 mumol/L). Responses were compared to those obtained with papaverine, which is used therapeutically as an erectogen. In addition, both agents improve in vitro responses of erectile tissue from HC rabbits to EFS.. The formation of cGMP was stimulated with increasing concentrations of sodium nitroprusside (SNP) and the cGMP and cAMP concentrations measured by radioimmunoassay. MATERIALS AND METHODS. At all stimulatory concentrations of SNP, the effective concentrations for 50% stimulation (EC50) ofSildenafil Citrate (Viagra) were 430-520 nmol/L. CONCLUSIONS There was a significantly lower in vivo and in vitro erectile response in HC rabbits than in controls; erectile function measured in conscious rabbits can be used to assess quantitatively the efficacy of different agents, e.g. However, the responses of the HC rabbits were still significantly less than those of the controls. Concentrations of cAMP were unaltered by sildenafil. Corpora from both HC and control rabbits had greater responses to EFS after exposure to Vardenafil ( Levitra ) and sildenafil; N'-nitro- l-arginine methyl sioux diminished the response to EFS. Male New Zealand White rabbits (2.5 kg) were killed and their penises rapidly excised, cut into segments and pooled.
|