BIOLOGICAL STUDIES OF A NITROSO COMPOUND THAT RELEASES NITRIC-OXIDE UPON ILLUMINATION

2-Methyl-2-nitrosopropane (MNP) has long been known to undergo photoch emical and thermal decomposition, generating di-tert-butyl nitroxide, in organic solvent. The present study was undertaken to demonstrate th at 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 an d by oxyhemoglobin/visible spectroscopy, respectively. Using soluble g uanylate cyclase in neuroblastoma N1E-115 cells as an NO target, we fo und that MNP in the presence of light caused a dose- and time-dependen t increase in cGMP. Finally, illumination of a solution of MNP was als o found to induce relaxation of preconstricted isolated rat pulmonary artery rings. These studies demonstrated that MNP can be a useful bioc hemical research tool for delivering NO in a controlled manner, by usi ng light.