Near-infrared spectroscopic measurement of myoglobin oxygen saturation in the presence of hemoglobin using partial least-squares analysis

Myoglobin is an important intracellular protein found in cardiac and skelet al muscle. It is involved in the intracellular transport of oxygen from the cell membrane to the mitochondria where oxidative phosphorylation takes pl ace, The optical absorbance characteristics of myoglobin are similar to tho se of hemoglobin in the near-infrared spectral region, Distinguishing spect ral information of myoglobin from hemoglobin should allow for determination of intracellular oxygen availability in muscle. Partial least-squares anal ysis is used in this report to determine the oxygen saturation of myoglobin , in the presence of hemoglobin, in vitro. Studies were performed with the use of both transmission and reflectance spectroscopic techniques, Transmis sion spectra of myoglobin solutions were determined with varying degrees of oxygen saturation achieved by deoxygenating the solution using E. coli. Ca libration spectral data sets were developed with the use of varying concent rations of hemoglobin interference, and with varying degrees of myoglobin o xygen saturation. Reflectance spectra were obtained from myoglobin and hemo globin solutions containing a scattering agent to mimic muscle tissue condi tions. Predicted myoglobin saturation values were within 2% of the known sa turation values from the use of this analysis, Partial least-squares analys is allows for accurate prediction of myoglobin oxygen saturation in the pre sence of hemoglobin from either transmission of reflectance near-infrared s pectra.