| This dissertation describes the instrumentation and a technique to use reflectance spectroscopy for determining intracellular myocardial oxygen partial pressure from a blood perfused living dog heart. Multi-wavelength optical spectroscopy was also used to determine accurate myoglobin oxygen dissociation curves.; Myoglobin oxygen dissociation curves were determined for temperatures of 10, 25, 35, 37 and 40{dollar}spcirc{dollar}C, at pH 7.0. In addition, dissociation curves were determined at 37 C for pH 6.5, 7.0 and 7.5. Correction for the inevitable presence of metmyoglobin was made using a three component least squares analysis, and by correcting the end-point oxymyoglobin spectra for the presence of metmyoglobin. A P{dollar}sb{lcub}50{rcub}{dollar} for myoglobin of 2.39 was determined at pH 7.0 and 37{dollar}spcirc{dollar}C, which compares favorably with published values.; Reflectance spectra were obtained from the surface of a beating canine heart, using a contacting bifurcated fiber optic probe, with a 3.0 mm minimum source to detector separation. Spectral acquisition was gated to the cardiac and respiratory cycles to minimize motion artifact. Constant perfusion of the coronary artery was maintained with either oxygenated blood or the non-hemoglobin blood substitute, Fluosol, to evaluate the sensitivity of the analysis to hemoglobin. Intra-coronary infusion of adenosine was used to maximally vasodilate the coronary artery. Reflectance spectra were interpreted using a calibration set of spectra developed in vitro in scattering media by the method of partial least squares analysis.; Partial least squares analysis of the in vivo reflectance spectra demonstrated a baseline myoglobin saturation of 89% while the animals breathed room air. An increase in saturation to 94% occurred with the use of inspired oxygen. Substitution of blood perfusion with Fluosol did not result in a significant change in the saturation values determined during adenosine and oxygen administration, or during occlusion of the coronary artery. |
