Chronic vardenafil treatment improves erectile function via structural maintenance of penile corpora cavernosa in rats with acute arteriogenic erectile dysfunction.

INTRODUCTION: Chronic phosphodiesterase type 5 inhibitor treatment may be useful in reversing erectile dysfunction (ED). However, the mechanisms of this improvement remain unknown.

AIM: The aim of this article was to determine the mechanisms of the improvement by chronic vardenafil treatment for acute arteriogenic ED in rats.

METHODS: Eight-week-old male Wistar-ST rats were divided into four groups: sham-operated rats (Control group) and rats with acute arteriogenic ED induced by ligating bilateral internal iliac arteries (Ligation group), subsequently treated with low-dose (0.4 mg/kg/day; VL group) or high-dose (4.0 mg/kg/day; VH group) vardenafil for 20 days from 1 week after ligature.

MAIN OUTCOME MEASURES: Erectile function was assessed based on changes of intracavernous pressure (ICP) followed by electrostimulation of the cavernous nerves and was evaluated by the area under the curve of ICP/area under the curve of mean arterial pressure (area of ICP/MAP). Transforming growth factor (TGF)-β(1), vascular endothelial growth factor-A, endothelial nitric oxide synthase (eNOS), inducible NOS, and neuronal NOS mRNA expression levels in penile corpus cavernosum were determined by real-time PCR. Western blotting for TGF-β(1) protein levels and Masson trichrome staining of penile tissues were performed in each at group 4 weeks after surgery.

RESULTS: In the VH group, area of ICP/MAP was significantly improved when compared with the Ligation group (P < 0.01). The smooth muscle (SM)/collagen ratio in the VH group was significantly higher than in the Ligation group (P < 0.05), and was comparable with that in the Control group. TGF-β(1) mRNA and protein levels in the VH group were significantly lower when compared with the Ligation group (P < 0.05).

CONCLUSIONS: Chronic vardenafil administration ameliorates impairment of penile hemodynamics and maintains normal SM to collagen ratio in cavernous tissues after acute arterial injury in rats.