Fig. 3. Schematic image and experimental protocol of intracavernous pressure (ICP) measurement Schematic image of ICP measurement experiment is shown in (A). Light source was set at a distance of 2 cm from the penis and red light was irradiated during electrostimulation. NORD-1 or SiR650 were injected into the penis using a T-shape stopcock. Experimental protocol is shown in (B). ICP was measured in three conditions; without injecting reagent and irradiating red-light, with reagent and without red-light, and with reagent and red-light, continuously.