Phosphorus nuclear magnetic resonance and ocular metabolism

Abstract

Phosphorus (31P) nuclear magnetic resonance (NMR) represents a noninvasive technique for the assessment of ocular metabolism. The measurement of a spectrum of phosphorus-containing metabolites (e.g., phosphorylated sugars and ATP), including a number of heretofore uncharacterized metabolites, can be made with a single analysis. In addition to quantitating phosphatic metabolites, 31P NMR can be employed to monitor (1) the rate of metabolic change in a specific biochemical reaction via T1 and T2 relaxation times, and (2) the rate of change in the concentration of a particular metabolite. Several calculations indicating tissue energy status (health) can be made using quantitative spectroscopic information including: the phosphorylation potential, the energy charge of the adenylate system, and the 31P spectral modulus. Tissue pH can be determined as a function of shift in 31P NMR signals. 31P NMR techniques have both research and diagnostic applications in ophthalmology since potentially it provides a noninvasive method to analyze ocular tissues metabolically and detect subtle biochemical changes that precede overt manifestation of disease states. Such detection may allow for early and more effective therapeutic intervention of disease. Furthermore, the noninvasive quality of NMR spectroscopy will permit continual evaluation of therapy.