Development of LCMS method for monitoring the effects of meat feasting, fasting, and exercise on urinary 3MH levels

Abstract

LCMS is a proven effective tool for automated quantitation of biological samples. This study describes an LCMS assay for time course studies of metabolites of interest to muscle physiology researchers. The primary advantage to the LCMS approach is the ability to monitor multiple metabolites simultaneously. 3‐methyl histidine (3MH), a skeletal muscle protein breakdown product, was chosen for these method development studies. To account for varying degrees of hydration of the urine samples, 3MH levels are normalized both against the ubiquitous creatinine and the darkness of the sample. Initially, a meat fast and feast were conducted to determine the time required for urinary 3MH levels to reach a baseline. Results suggest that a 24hr meat fast is sufficient prior to intervention and sample collection. To evaluate the method's ability to observe changes in urinary metabolite levels in response to exercise, 3MH levels were monitored in 8 subjects following aerobic (70% HR max, 45min), interval (4 intervals of 3min at 90–95% and 70% HR max), and resistance training (2 sets to fatigue on 8 exercise machines). The exercise that stimulated the greatest 3MH excretion varied among the subjects.