2-2-5-5-tetramethyl-1-pyrrolidinyloxy-3-carboxylic-acid and 1-1-diphenyl-2-picrylhydrazyl

Electron paramagnetic resonance imaging (EPRI) is currently being developed at frequencies between 200 MHz and 2 GHz. EPRI can map the in vivo distribution of paramagnetic species, such as water soluble free radicals; nitroxide free radicals are commonly used. EPR images reflect the complexity of metabolic actions on the exogenous delivered nitroxides. Their reduction rate in vivo is affected by parameters such as oxygen concentration, pH and biodistribution. This paper illustrates the main features of low frequency EPRI and reconstruction techniques. Examples of EPR imaging, such as two-dimensional (2D) spatial mapping of the distribution of a nitroxide free radical in phantoms and in whole rat, are given.

Topics: Animals; Bepridil; Biphenyl Compounds; Cyclic N-Oxides; Electron Spin Resonance Spectroscopy; Free Radicals; Image Processing, Computer-Assisted; Liposomes; Nitric Oxide; Picrates; Rats; Rats, Wistar; Solubility; Spin Labels; Water

Low frequency (280 MHz) electron paramagnetic resonance spectroscopy has been used to follow uptake, distribution and reduction of the nitroxyl spin label PCA in the rat. No difference of half life was found in seven rats submitted to three administrations of PCA (11.3 +/- 0.4; 11.0 +/- 0.6 and 11.5 +/- 0.7 min). Transversal two-dimensional images of PCA distribution in the rat body were obtained over 6 min by means of field gradients. PCA was observed in three regions by projections along the longitudinal axis of the rat. PCA accumulation was found in the lower abdomen 12 min after the start of the PCA injection.

Topics: Animals; Bepridil; Biphenyl Compounds; Cyclic N-Oxides; Diagnostic Imaging; Electron Spin Resonance Spectroscopy; Functional Laterality; Injections, Intravenous; Picrates; Radio Waves; Rats; Rats, Inbred Strains; Spectrum Analysis; Spin Labels