Illumination with blue light reactivates respiratory activity of mitochondria inhibited by nitric oxide, but not by glycerol trinitrate.

Nitric oxide (NO) is known to inhibit mitochondrial respiration reversibly. This study aimed at clarifying whether low level illumination at specific wavelengths recovers mitochondrial respiration inhibited by NO and glycerol-trinitrate (GTN), a clinically used NO mimetic. NO fully inhibited respiration of liver mitochondria at concentrations occurring under septic shock. The respiration was completely restored by illumination at the wavelength of 430nm while longer wavelengths were less effective. GTN inhibited mitochondrial respiration though the efficiency of GTN was lower compared to NO concentrations observed in sepsis models. However, GTN inhibition was absolutely insensitive to illumination regardless of wavelength used. Our data show that visible light of short wavelengths efficiently facilitates the recovery of mitochondria inhibited by NO-gas at the levels generated under septic conditions. The inhibition of mitochondrial respiration by GTN is not sensitive to visible light, suggesting an inhibition mechanism other that NO mediation.