Deletion of CD73 increases exercise power in mice

Abstract

Ecto-5'-nucleotidase CD73 is the main source of extracellular adenosine involved in the activation of adenosine A2A receptors responsible for the ergogenic effects of caffeine. We now investigated the role of CD73 in exercise by comparing female wild-type (WT) and CD73 knockout (KO) mice in a treadmill graded test to evaluate running power, oxygen uptake (VO2), and respiratory exchange ratio (RER) - the gold standards characterizing physical performance. Spontaneous locomotion in the open field and submaximal exercise performance in the treadmill were similar between CD73-KO and WT mice; VO2max also demonstrated equivalent aerobic power. However, CD73-KO displayed higher anaerobic power indexes, namely a 43.7[plusmn]4.2% larger critical power (large effect size, P <0.05) and 3.8[plusmn]0.4 increase of maximum RER (small effect size, P <0.05). Thus, KO of CD73 was ergogenic, i.e., it increased physical performance, suggesting that CD73-mediated formation of extracellular adenosine signals fatigue.