Light-controlled relaxation of the rat penile corpus cavernosum using NOBL-1, a novel nitric oxide releaser

Purpose: To investigate whether relaxation of the rat penile corpus cavernosum could be controlled with NOBL-1, a novel, lightcontrollable nitric oxide (NO) releaser. Materials and Methods: Fifteen-week-old male Wistar-ST rats were used. The penile corpus cavernosum was prepared and used in an isometric tension study. After noradrenaline (10⁻⁵ M) achieved precontraction, the penile corpus cavernosum was irradiated by light (470–500 nm) with and without NOBL-1 (10⁻⁶ M). In addition, we noted rats’ responses to light with vardenafil (10⁻⁶ M), a phosphodiesterase-5 (PDE-5) inhibitor. Next, responses to light in the presence of a guanylate cyclase inhibitor, ODQ (1H-[1,2,4] oxadiazolo[4,3-a]quinoxalin-1-one) (10⁻⁵ M), were measured. All measurements were performed in pretreated L-NAME (10⁻⁴ M) conditions to inhibit endogenous NO production. Results: Corpus cavernosal smooth muscle, precontracted with noradrenaline, was unchanged by light irradiation in the absence of NOBL-1. However, in the presence of NOBL-1, corpus cavernosal smooth muscle, precontracted with noradrenaline, relaxed in response to light irradiation. After blue light irradiation ceased, tension returned. In addition, the light response was obviously enhanced in the presence of a PDE-5 inhibitor. Conclusions: This study showed that rat corpus cavernosal smooth muscle relaxation can be light-controlled using NOBL-1, a novel, light sensitive NO releaser. Though further in vivo studies are needed to investigate possible usefulness, NOBL-1 may be prove to be a useful tool for erectile dysfunction therapy, specifically in the field of penile rehabilitation.