Simultaneous Optical Spectroscopic Measurement of Hemoglobinand Myoglobin Saturations and Cytochrome aa3 Oxidation In Vivo

摘要

A method to simultaneously measure oxygenation in vascular, intracellular,nand mitochondrial spaces from optical spectra acquired fromnmuscle has been developed. In order to validate the method, opticalnspectra in the visible and near-infrared regions (600–850 nm) werenacquired from solutions of myoglobin, hemoglobin, and cytochromenoxidase that included Intralipid as a light scatterer. Spectra were alsonacquired from the rabbit forelimb. Three partial least squares (PLS)nanalyses were performed on second-derivative spectra, each separatelyncalibrated to myoglobin oxygen saturation, hemoglobin oxygen saturation,nor cytochrome aa3 oxidation. The three variables were measured from innvitro and in vivo spectra that contained all three chromophores. In the innvitro studies, measured values of myoglobin saturation, hemoglobinnsaturation, and cytochrome aa3 oxidation had standard errors of 5.9%,n7.4%, and 12.2%, respectively, with little cross-talk between the in vitronmeasurements. In the progression from normal oxygenation to ischemia innthe rabbit forelimb, hemoglobin desaturated first, followed by myoglobin,nwhile cytochrome aa3 reduction occurred last. The ability to simultaneouslynmeasure oxygenations in the vascular, intracellular, andnmitochondrial compartments will be valuable in physiological studies ofnmuscle metabolism and in clinical studies when oxygen supply ornutilization are compromised.