Light-controlled relaxation of rat penile corpus cavernosum by a novel NO donor, NO-Rosa
Hotta, Y1; Ieda, N1; Kataoka, T1; Maeda, Y1; Nakagawa, H1; Kimura, K1
1: Nagoya City University, Japan
Objective. Phosphodiesterase-5 inhibitors are not always effective for patients with erectile dysfunction (ED) who also have diabetes mellitus or have had a radical prostatectomy, because of the reduction in nitric oxide (NO) production. The control of NO production may be useful as a therapy for ED. In this study, we focused on a light-controllable NO releaser. Previously, we developed a blue (470–500 nm) light-controllable NO releaser, NOBL-1. Subsequently, we improved NOBL-1, because blue light has low tissue permeability. We have now succeeded in the development of a yellow-green (530–590 nm) light-controllable NO releaser, NO-Rosa. We investigated whether we could control the relaxation of the corpus cavernosum smooth muscle by using an NO-Rosa derivative and light irradiation.
Materials and Methods. Fluorescence imaging of the NO release from NO-Rosa in HEK-293 cells was performed using DAF-FM. Adult male Wistar-ST rats were used for the isometric tension study. The corpus cavernosum was treated by the addition of L-NAME (100 μM) to inhibit endogenous NO production and pre-contracted with noradrenaline (10 μM). The response of the corpus cavernosum smooth muscle to irradiation with yellow-green light, before and after the addition of an NO-Rosa derivative (10 μM), was measured and recorded.
Results. NO release in HEK-293 cells treated with NO-Rosa was observed in response to yellow-green light irradiation, whereas this did not occur in the cells not treated with NO-Rosa. The rat corpus cavernosum smooth muscle relaxed when irradiated with yellow-green light in the presence of the NO-Rosa derivative, whereas light irradiation did not cause any change in the corpus cavernosum smooth muscle in the absence of the derivative. This relaxation response to yellow-green light persisted during irradiation. In addition, after irradiation was stopped, relaxation in the presence of the NO-Rosa derivative disappeared and tension returned.
Conclusions. This study demonstrated the control of the relaxation of the corpus cavernosum smooth muscle by using an NO-Rosa derivative, a novel yellow-green light-controllable NO releaser. Although further in vivo studies are required for confirmation, our results suggested that the NO-Rosa derivative may be a useful tool for penile rehabilitation or ED therapy.
Work supported by industry: no.Go Back