Reversibility of heme-nitric oxide reactions for use in an inhaled nitric oxide sensor

摘要

Nitric Oxide is a simple gaseous compound which serves as a regulatory molecule in a number of physiological processes. Due to its biological role as a potent local vasodilator,there has been widespread interest in the therapeutic use of gaseous nitric oxide a selective pulmonary vasodilator. Our goal is the development of a sensor for the direct and continuous measurement of inhaled nitric oxide concentrations. This study evaluated the reversibility of potential sensing compounds upon reaction with nitric oxide. Previously, absorption spectroscopy was used to study the sensitivity of the Fe II, Fe III and oxygenated forms of three biologically active hemes known to rapidly react with NO: hemoglobin, myoglobin, and cytochrome-c. This study focused on the photo-reversibility of the hem's reaction with nitric oxide. Hemoglobin, myoglobin and cytochrome-c in the Fe III state reversibly reacted with nitric oxide. Hemoglobin and myoglobin in the Fe II state non-reversibly reacted with nitric oxide to form an unstable product. Cytochrome-c (FeII) does not react with nitric oxide. The oxy forms of hemoglobin and myoglobin react with nitric oxide to form their respective met forms, unreversible via photolysis. For all reversible reactions, photolysis was gradual and complete within five minutes.