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)-β1, 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-β1 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-β1 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.

Temporal changes in the germination flux of cysts and the abundance of vegetative cells of the toxic dinoflagellate were investigated in Ago Bay, central Japan from July 2003 to December 2004. The germination flux (cells m day) was measured using 'plankton emergence trap/chambers (PET chambers)'. Germination of the cysts in the sediments occurred continuously during the study, ranging from 52 to 1753 cells m day, with no temporal trend. This germination pattern appeared to be promoted by a short mandatory dormancy period for newly formed cysts coupled with a broad temperature window for germination. For the vegetative populations, high abundances (>10 cells m) were recorded in the water column from spring to summer and from autumn to early winter. The size of the vegetative populations did not correlate with the cyst germination flux but rather larger vegetative populations were often observed when the water temperature was around 20°C, indicating that bloom development was mainly regulated by the temperature. Nonetheless, the continuous germination pattern of is advantageous enabling the germinated cells to immediately exploit favorable bloom conditions.

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