INFLUENCE OF AGING OR LEFT-VENTRICULAR HYPERTROPHY ON THE HUMAN HEART- CONTENTS OF PHOSPHORUS METABOLITES MEASURED BY P-31 MRS

Although both aging and hypertrophy are extremely important factors fo r cardiac performance, their influence on cardiac metabolism, especial ly that of high-energy phosphates, has not been fully elucidated as ye t. Quantitative measurements of high-energy phosphates were attempted by comparing myocardial P-31 NMR spectra with an external reference us ing depth-resolved surface-coil spectroscopy, The voxel size of the re gion of interest (ROI) was disk-shaped with 15-cm diameter and 25-mm t hickness, but the left ventricular weight actually involved in the ROI was estimated to be between 22 and 66 g using MRI, Myocardial phospho creatine (PCr) content and adenosine triphosphate (ATP) content for th e 30 normal volunteers showed significant age dependence since both de creased in relation to increasing age. Myocardial PCr content and ATP content in patients with hypertension did not differ significantly fro m the age-matched control group. PCr content (6.1 +/- 2.2 mu mol/g wet tissue, n = 10) and ATP content (4.1 +/- 1.3 mu mol/g wet tissue) in patients with hypertrophic cardiomyopathy were less than the age-match ed control group (n = 15; PCr: 9.7 +/- 2.5 mu mol/g wet tissue, P < 0. 01; ATP: 6.4 +/- 1.8 mu mol/g wet tissue, P < 0.05), respectively. The se results indicate that quantitative P-31 MRS may be valuable in the assessment of changes in high-energy phosphate metabolism caused by ag ing or hypertrophy.