Optical imaging of tissue mitochondrial redox state in intact rat lungs in two models of pulmonary oxidative stress

Abstract

Ventilation with enhanced fractions of O(2) (hyperoxia) is a common and necessary treatment for hypoxemia in patients with lung failure, but prolonged exposure to hyperoxia causes lung injury. Ischemia-reperfusion (IR) injury of lung tissue is common in lung transplant or crush injury to the chest. These conditions are associated with apoptosis and decreased survival of lung tissue. The objective of this work is to use cryoimaging to evaluate the effect of exposure to hyperoxia and IR injury on lung tissue mitochondrial redox state in rats. The autofluorescent mitochondrial metabolic coenzymes nicotinamide adenine dinucleotide (NADH) and flavin adenine dinucleotide (FAD) are electron carriers in ATP generation. These intrinsic fluorophores were imaged for rat lungs using low-temperature fluorescence imaging (cryoimaging). Perfused lungs from four groups of rats were studied: normoxia (control), control perfused with an mitochondrial complex IV inhibitor (potassium cyanide, KCN), rats exposed to hyperoxia (85% O(2)) for seven days, and from rats subjected to lung IR in vivo 24 hours prior to study. Each lung was sectioned sequentially in the transverse direction, and the images were used to reconstruct a three-dimensional (3-D) rendering. In KCN perfused lungs the respiratory chain was more reduced, whereas hyperoxic and IR lung tissue have a more oxidized respiratory chain than control lung tissue, consistent with previously measured mitochondrial dysfunction in both hyperoxic and IR lungs.

Organ specific optical imaging of mitochondrial redox state in a rodent model of hereditary hemorrhagic telangiectasia‐1

“…Thus, the measurement of mitochondrial metabolic activity could potentially be an early indicator of organ dysfunction during the disease. Our present method measures fluorescence from both NADH and FAD, allowing calculations of the redox ratio, which has proven to be a powerful diagnostic marker, independent of the number of mitochondria and hemodynamics [50, 65, 76]. Furthermore, this study demonstrates the ability of cryoimaging to measure FAD RR of various organs.…”

Effect of temperature on FAD and NADH-derived signals and neurometabolic coupling in the mouse auditory and motor cortex

“…Redox ratio is an established marker for the metabolic state of different tissue types including brain [97,65,25,90]. To determine if the temperature-dependent changes in FAD signals and neurometabolic signals described above were related to changes in resting redox state, both raw FAD and NADH endogenous fluorescence signals of brain slices were measured at different temperatures.…”

Hyperspectral imaging fluorescence excitation scanning for colon cancer detection

“…In the long term, a spectral library of fluorescence excitation spectra could be used to assist physicians in the diagnostic process in several ways: (1) by providing an estimate of tissue composition for specified areas of interest, (2) by providing molecular maps of a tissue using linear unmixing 67,68 or other spectral analysis technique, 69-71 (3) by allowing calculation of derived maps (such as redox ratio 72,73 or blood oxygen saturation [74][75][76] ), which may correlate with cancer development. If unmixing or spectral analysis is performed, it may be advantageous to employ more sophisticated nonlinear unmixing approaches, especially if reflectance and fluorescence image data can be combined to better estimate tissue parameters, such as scatter.…”