Injectable Phosphorescence-based Oxygen Biosensors Identify Post Ischemic Reactive Hyperoxia.
Novel injectable biosensors were used to measure interstitial oxygenation before, during, and after
transient ischemia. It is well known that reactive hyperemia occurs following a period of ischemia.
However, increased blood flow does not necessarily mean increased oxygen tension in the tissue.
Therefore, the purpose of this study was to test the hypothesis that tissue reactive hyperoxia
occurs following release of hind-limb tourniquet occlusions. Rats were injected with bilateral hindlimb
biosensors and were simultaneously subjected to a unilateral femoral vessel ligation. After
approximately one and three months, the rats underwent a series of oxygenation challenges, including
transient hind-limb tourniquet occlusion. Along with the biosensors, near infrared spectroscopy
was used to measure percent oxyhemoglobin in capillaries and laser Doppler flowmetry was used
to measure blood flow. Post-occlusion reactive hyperemia was observed. It was accompanied by
tissue reactive hyperoxia, affirming that the post-occlusion oxygen supply must have exceeded the
expected increased oxygen consumption. The measurement of the physiologic phenomenon of reactive
hyperoxia could prove clinically beneficial for both diagnosis and optimizing therapy.
Klitzman, B; Chien, JS; Mohammed, M; Eldik, H; ibrahim, M; Martinez, J; Nichols, SP; Wisniewski, NA
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