Extract

Objective

In our previous study, we developed some light-controlled NO donors. However, the low tissue permeability of those NO donors are problem. Thus, to improve tissue permeability, we developed a novel near-infrared light-controlled NO donor, NORD-1. In this study, we investigated whether NORD-1 and light irradiation could control the relaxation of the penile corpus cavernosum by conducting in vitro and in vivo studies using rats.

Methods

[In vitro study] An isometric tension study was performed using the penises with tunica albuginea of intact Wistar-ST rats injected with NORD-1 or vehicle in the penis. The response to light irradiation was examined after precontraction with noradrenaline. [In vivo study] Intracavernous pressure (ICP) was measured to evaluate erectile function, under electrostimulation of the cavernous nerve (1, 2, 4, and 8 Hz) before and after injection of NORD-1 to the penile corpus cavernosum, with or without light irradiation.

Results

[In vitro study] a relaxing response to light irradiation was observed in the penises with tunica albuginea injected with NORD-1, but not in those injected with vehicle. The strength of the relaxation depended on the strength of the light irradiation. [In vivo study] The increased ICP by electrostimulation under light irradiation and NORD-1 treatment was obviously enhanced strength-dependently. Before the NORD-1 treatment, light irradiation did not change the increase in ICP.

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