Simultaneous optical and nuclear magnetic resonance spectroscopy for monitoring cardiac energetics in vivo

There are a number of applications in which it is useful to simultaneously collect data from what are traditionally separate instrumentation modalitie s. In particular, in vivo physiological investigations in which data from p arallel experiments must be correlated would benefit from simultaneous data collection through 1) elimination of subject variability, 2) elimination o f treatment variability, and 3) a reduction in the number of animal prepara tions required, Here we describe the simultaneous collection of fluo-3 opti cal fluorescence and P-31 nuclear magnetic resonance (NMR) spectra to measu re intracellular calcium levels and high-energy phosphate metabolism, respe ctively; in vivo. This work is part of ongoing research into the profound a noxia tolerance exhibited by the hearts of certain turtle species, An NMR c ompatible optical fluorescence spectrometer was constructed and tested. In the 31-cm bore of a 2 T superconducting magnet, NMR and optical spectra wer e collected every 10-15 min from the irt situ, in vivo hearts of anesthetiz ed turtle subjects prior to and during one to three hours of anoxia, It was found that while PCr stores became significantly depleted during anoxia, b eta-adenosine triphosphate (ATP) levels remained within 20% of control valu es, and intracellular diastolic calcium levels did not vary by more than 10 %. The ability to make simultaneous phosphorus and calcium measurements on a single subject is important to understanding the exact relationship betwe en phosphorus energy state and maintenance of calcium homeostasis.