Despite the wealth of knowledge about the chemistry of nitric oxide (NO), there is considerable uncertainty regarding the reactions of NO in vivo. One goal of this research is to characterize the interaction of nitric oxide with protein-bound iron, typically with thiol ligands. A second goal of the research is to use dithiocarbamates as in vivo spin traps for NO in mice, allowing the real-time detection of NO through L-band EPR spectroscopy and the ex vivo analysis of individual organs through X-band spectroscopy. This technique has been successful for detecting NO production in mouse septic shock models, utilizing diethyl dithiocarbamate (DETC) and N-methyl-D-glucamine dithiocarbamate injected along with iron(II) sulfate and sodium citrate. The EPR signal observed is characteristic of a mononitrosyl iron complex; in L-band spectroscopy it consists of an essentially symmetrical triplet with splitting of approximately 12.8 Gauss due to the nitrogen. In the current trials, the signal produced by the Fe-DETC-NO complex has a greater intensity, likely due to its greater lipophilicity and ability to concentrate in cell membranes. Future work will involve testing a variety of other dithiocarbamates, including the sarcosine, pyrrolidine, and proline derivatives, in order to maximize the spectrum from trapped NO in the liver, kidney, brain, spinal cord, and in circulation.
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