The Superoxide Scavenger And Antioxidant, L-Propionyl-carnitine, Is Metabolically Enhanced Following Exercise In Hypoxia

Abstract

L-Propionyl-carnitine, a propionyl ester of L-carnitine, is known to scavenge the superoxide anion, inhibit lipid peroxidation, and protect against H2O2-induced DNA strand scission. While exogenous L-propionyl-carnitine supplementation modulates lipid peroxidation in humans, the endogenous metabolic response following exercise is currently unknown. PURPOSE: To investigate the metabolic profile of L-propionyl-carnitine following exercise in hypoxia. METHODS: Twenty-four (n=24) apparently healthy male participants were recruited (age 28 ± 5 years; mass 74 ± 8 kg; stature 177 ± 6 cm; 2max hypoxia 45 ± 2 ml·kg-1·min-1: normoxia 60 ± 9 ml·kg-1·min-1), and completed 1 hr of exercise at a workload corresponding to 75% of pre-determined 2max in hypoxia (Fio2 = 0.16%), and repeated in normoxia (Fio2 = 0.21%). Serum L-propionyl-carnitine was quantified using a LC ESI-qTOF-MS untargeted metabolomics approach at pre-, post-exercise and 3 h post-exercise (Recovery). RESULTS: Exercise performed in hypoxia and normoxia independently increased L-propionyl-carnitine metabolism (p<0.05, pre vs. post-exercise), and hypoxia per se did not induce a selective metabolic change when compared to normoxia (p>0.05). Recovery from exercise was similar for both hypoxia and normoxia (p<0.05, post vs. 3 hrs post-exercise). There was a main effect for time observed for pooled hypoxia and normoxia values (pre vs. post-exercise vs. 3 hrs post-exercise, p<0.05). CONCLUSION: This is the first data to show a metabolic response in L-propionyl-carnitine following exercise. As such, we propose the increased mobilisation of L-propionyl-carnitine may be beneficial to counteract deleterious free radical production and protect against vascular exercise-induced oxidative stress.