THE EFFECTS OF AGE ON PHOSPHATIC METABOLITES OF THE HUMAN CORNEA

Phosphatic metabolites from human corneas, pooled into 7 decades rangi ng from ages <1 year through 79 years, were quantitated using phosphor us-31 magnetic resonance (P-31 MR) spectroscopy. Relative concentratio ns of phosphorus-containing compounds measured included the low-energy metabolites [phosphomonoesters (PME), inorganic orthophosphate (Pi), phosphodiesters (glycerol 3-phosphorylethanolamine and glycerol 3-phos phorylcholine)] and the high-energy metabolites [phosphocreatine (PCr) , adenosine triphosphate (ATP), adenosine diphosphate (ADP), nucleosid ediphosphosugars and the dinucleotides]. Significant linear changes at tributable to age occur in the relative mole percentage decrease of ph osphate concentrations of human corneal PME, PCr and ATP, and in the i ncrease of Pi. Age-attributable rates of decrease in PME at -0.162 MPP /YR (mole percent phosphorus per year), PCr at -0.015 MPP/YR and ATP a t -0.487 MPP/YR combined, approximate the rate of increase in Pi deter mined to be +0.729 MPP/YR. Of the indices computed from the human corn eal spectral data, the ratios of ATP/Pi and PME/Pi and the tissue ener gy modulus were all found to decrease significantly with age. These ch anges in corneal phosphatic metabolites are indicative of an overall d ecline in high-energy metabolism with age.