Biological studies of a nitroso compound that releases nitric oxide upon illumination

2-Methyl-2-nitrosopropane (MNP) has long been known to undergo photochemical and thermal decomposition, generating di-tert-butyl nitroxide, in organic solvent. The present study was undertaken to demonstrate that MNP can be used as a caged-nitric oxide (NO), which can liberate NO upon illumination. Photolysis of MNP leads to the generation of tert-butyl radical and NO, as detected by spin-trapping/ESR spectroscopy and by oxyhemoglobin/visible spectroscopy, respectively. Using soluble guanylate cyclase in neuroblastoma N1E-115 cells as an NO target, we found that MNP in the presence of light caused a dose- and time-dependent increase in cGMP. Finally, illumination of a solution of MNP was also found to induce relaxation of preconstricted isolated rat pulmonary artery rings. These studies demonstrated that MNP can be useful biochemical research tool for delivering NO in a controlled manner, by using light.