Effects of nicotinamide N-methyltransferase (NNMT) inhibition on the aerobic and the anaerobic endurance exercise capacity

Abstract

Summary Introduction Numerous reports showed that nicotinamide N-methyltransferase (NNMT) plays important roles in the regulation of energy metabolism and in the synthesis of ATP, which indicates that the activity of NNMT may be associated with sport performance. Methods and results To test this speculation, we inhibited NNMT activity of the rats with N-methylnicotinamide (MNA) (MNA group), and observed the effects on the lactate threshold and the maximal blood lactate concentration, and on the performance in the competitions of anaerobic and aerobic endurance exercise, respectively. The results showed: (1) the workloads (% body weight) of the rats in the swimming have no significant differences between MNA group and control group when the lactate threshold appeared (4.54 ± 0.90 vs. 4.60 ± 1.06), and when the maximal exercise intensity (exhaustion) appeared (6.00 ± 0.54 vs. 6.00 ± 0.81); (2) the rats of MNA group showed highly significantly lowered blood lactate concentrations than those of the control group immediately after the swimming with the maximal workload (10.40 ± 1.39 vs. 11.67 ± 1.71 mmol/L), 2 min post-exercise (11.49 ± 1.38 vs. 12.82 ± 1.63 mmol/L) and 4 min post-exercise (12.84 ± 1.36 vs. 14.3 ± 1.54 mmol/L); (3) in the anaerobic endurance exercise competition, 8 rats of the MNA group while 16 of the control group entered the top 24 places in the rank; (4) in the anaerobic endurance exercise competition, the swimming durations from the beginning until exhaustion were not significantly different between the MNA group and the control group (345.37 ± 71.69 vs. 345.30 ± 72.02 min). Conclusion These results suggest that NNMT inhibition significantly impairs the performance in anaerobic endurance exercise but not in aerobic endurance exercise.