Effect of acute administration of sildenafil to rats with detrusor overactivity induced by chronic deficiency of nitric oxide.

PURPOSE

Recently, the effect of phosphodiesterase inhibitors (PDE5i) in the lower urinary tract symptoms (LUTS) associated to benign prostatic hyperplasia have been studied thoroughly. However, it remains unclear how the PDE5i improve LUTS. Therefore, the aim of the present study was to evaluate the potential of acute administration of the PDE5i sildenafil to improve detrusor overactivity (DO) induced by Nω-nitro-L-arginine methyl ester hydrochloride (L-NAME), an nitric oxide sinthase (NOS) inhibitor, in rats.

MATERIALS AND METHODS

Twenty-seven MALE adult Wistar Rats were divided into the following groups: (1) control, (2) L-NAME, (3) sildenafil alone, and (4) L-NAME + sildenafil. The NOS blocker L-NAME (20 mg/rat/day) was given in the drinking water. Sildenafil (100 µg/kg) was administrated intravenously (i.v.) acutely, diluted in cremophor, propylene glycol and water. All animals underwent to anesthetized cystometograms.

RESULTS

The chronic and systemic administration of L-NAME markedly increased the number of non voiding contractions (2.62 (± 0.89)), and frequency of micturition (1.97 (± 0.78)), as well increased volume threshold (2.83 mL (± 1.64)) compared with control group, the number of non voiding contractions (1.17 (± 0.75)), frequency of micturition (1.08 (± 0.65)) and volume threshold (1.16 mL (± 0.38)), p < 0.001, p = 0.01, and p = 0.04, respectively. Sildenafil infusion decreased the number of micturition cycles significantly from the baseline to end point (-0.93 (± 0.34)) in nitric oxide (NO) deficient animals compared with sildenafil infusion alone (control) in animals with normal NO level (0.13 (± 0.25)), p = 0.03.

CONCLUSION

Systemic reduction of nitric oxide causes detrusor overactivity and acute infusion of sildenafil reduces the number of micturition cycles in chronic NO-deficient rats.