Nitric oxide is an important messenger in numerous biological processes, such as angiogenesis, hypoxic vasodilation, and cardioprotection. Although
nitric oxide synthases (NOS) produce the bulk of NO, there is increasing interest in NOS independent generation of NO in vivo, particularly during
hypoxia or
anoxia, where low
oxygen tensions limit NOS activity. Interventions that can increase NO bioavailability have significant therapeutic potential. The use of far red and near infrared light (R/NIR) can reduce
infarct size, protect neurons from
methanol toxicity, and stimulate angiogenesis. How R/NIR modulates these processes in vivo and in vitro is unknown, but it has been suggested that increases in NO levels are involved. In this study we examined if R/NIR light could facilitate the release of NO from nitrosyl
heme proteins. In addition, we examined if R/NIR light could enhance the protective effects of
nitrite on
ischemia and
reperfusion injury in the rabbit heart. We show both in purified systems and in myocardium that R/NIR light can decay nitrosyl hemes and release NO, and that this released NO may enhance the cardioprotective effects of
nitrite. Thus, the photodissociation to NO and its synergistic effect with
sodium nitrite may represent a noninvasive and site-specific means for increasing NO bioavailability.