Please click here to obtain permission to reproduce this image.
Click on image to view larger version.
Figure 4 EPR Spectroscopy Detection of Iron in Carotid Plaques
Electron paramagnetic resonance (EPR) is a powerful and minimally invasive technique to identify and quantify the presence of paramagnetic ferric iron [Fe(III)] within an explanted carotid specimen. The EPR spectra were recorded on frozen tissue at 77 K. For further experimental details and spectrometer settings, see the Methods section. Representative EPR spectra from control carotid artery (A), asymptomatic patient’s carotid plaque (B), and symptomatic patient’s carotid plaque (C) are shown. Atherosclerotic plaque samples demonstrate the high-spin rhombic iron species peak at a magnetic field of  1,500 Gauss, corresponding to a g value of 4.3. Although no rhombic iron signal was observed in control carotid tissue, a prominent signal was present in asymptomatic patients’ carotid plaques; however, in symptomatic patients’ plaques, the level of this signal was significantly decreased.
|
