Sense and Sensibility of Oxygen in Pathophysiology Using EPR Oximetry

Abstract

Physiological homeostasis in aerobic organisms is strictly maintained by optimal cellular and tissue oxygen levels through intricate oxygen-sensing mechanisms, signaling cascades, and transport processes. Molecular oxygen is at the center of oxygenation, oxidative phosphorylation, and oxidative stress. An increase (hyperoxia) or decrease (hypoxia) in cellular oxygen level may result in altered cell-signaling cascades and redox imbalance leading to pathophysiological processes including cell death and tissue damage. Hypoxia has been implicated as a critical factor influencing the outcomes for several diseases, including cardiovascular diseases (myocardial infarction, ischemic stroke, and peripheral arterial disease), cancer, wound healing, and diabetic foot ulcer. The capability to measure tissue oxygenation in a reliable and repeated manner will be immensely useful for correct prognosis and treatment. This chapter focuses on the methods, particularly electron paramagnetic resonance (EPR) oximetry for quantitative measurement of tissue oxygenation using implantable oxygen sensors. Representative examples for cardiovascular and cancer applications are presented.