Salivary mtDNA copy number: index of aerobic efficiency? (705.6)

Objective: Mitochondrial DNA (mtDNA) is central to oxidative phosphorylation and energy production. mtDNA copy number (mtDNAcn) may serve as an index of mitochondrial density, but has not been well studied in saliva. Our goal was to determine whether salivary mtDNAcn is related to measures of aerobic efficiency and fitness. Methods: 15 men (32±8.3 yrs) volunteered for this study and performed exercise challenge testing, completed physical activity questionnaires, and provided a saliva sample for mtDNAcn analysis. Relative mtDNAcn was determined by real‐time PCR in saliva DNA from individuals. Subjects were assigned to HIGH and LOW aerobic efficiency groups based on the ratio of ventilation and oxygen consumption (Ve/VO 2 ). Variables of interest were mtDNAcn, maximum oxygen consumption (VO 2 /kg), respiratory exchange ratio (RER) and physical activity scores. Results: Ve/VO 2 was significantly correlated with relative mtDNAcn (R 2 =0.32, p=0.03). HIGH aerobic efficiency group had significantly higher mtDNAcn (t=2.34, p=0.03), VO 2 /kg (t=3.25, p<0.01), physical activity scores (t=2.24, p=0.04) and a lower RER (t=2.50, p=0.03) than LOW aerobic efficiency group. Conclusions: mtDNAcn is related to aerobic efficiency such that individuals with HIGH aerobic efficiency have significantly greater mtDNAcn. Future studies may consider salivary mtDNAcn in the evaluation of exercise tolerance and efficiency. Grant Funding Source : VA Grants 1I21RX001079‐01 and 1I21CX000797‐01