Age Dependence of Human gastrocnemius Mg ²⁺: Fitting ³¹P-NMR Spectra Using Quantum Mechanics-Based Prior Knowledge

Abstract

The age dependence of human gastrocnemius Mg²⁺ concentration is demonstrated. To quantitate Mg²⁺ concentration, an original and accurate fitting algorithm using quantum mechanics-based prior knowledge is detailed. In a group of 28 volunteers (14 females) in the age range 5-80 years, pH, PCr/ATP and Pi/ATP values in the gastrocnemius were 7.02 ± 0.02 pH, 4.16 ± 0.33 and 0.13 ± 0.02, respectively and independent of age and sex. By contrast, intracellular Mg²⁺ concentration (mM) decreased linearly (p<0.05) with age (Mg²⁺ = 0.7803 ± 0.0247-0.0027 ± 0.0005 * age). No difference was found between sexes. From these results, it follows that care must be taken when comparing muscle Mg²⁺ data from subjects of different age. The hypothesis can be put forward that during aging insufficient intake and/or increased depletion of Mg²⁺ (e.g., intestinal hypoabsorption or urinary leakage) may affect the musculoskeletal system.