L-Arginine enhances aerobic exercise capacity in association with augmented nitric oxide production

We tested whether supplementation with L-arginine can augment aerobic capac ity, particularly in conditions where endothelium-derived nitric oxide (EDN O) activity is reduced. Eight-week-old wild-type (E+) and apolipoprotein E- deficient mice (E-) were divided into six groups; two groups (LE+ and LE-) were given L-arginine (6% in drinking water), two were given D-arginine (DE + and DE-), and two control groups (NE+ and NE-) received no arginine suppl ementation. At 12-16 wk of age, the mice were treadmill tested, and urine w as collected after exercise for determination of EDNO production. NE- mice demonstrated a reduced aerobic capacity compared with NE+ controls [maximal oxygen uptake ((V) over dot O-2 max) of NE- = 110 +/- 2 (SE) vs. NE+ = 122 +/- 3 ml O-2.min(-1).g(-1), P < 0.001]. This decline in aerobic capacity w as associated with a diminished postexercise urinary nitrate excretion. Mic e given L-arginine demonstrated an increase in postexercise urinary nitrate excretion and aerobic capacity in both groups ((V) over dot O-2 max of LE- = 120 +/- 1 mi O-2.min(-1).kg(-1) P < 0.05 vs. NE-; (V) over dot O-2 max o f LE+ = 133 +/- 4 ml O-2.min(-1).kg(-1), P < 0.01 vs. NE+). Mice administer ed D-arginine demonstrated an intermediate increase in aerobic capacity in both groups. We conclude that administration of L-arginine: restores exerci se-induced EDNO synthesis and normalizes aerobic capacity in hypercholester olemic mice. In normal mice, L-arginine enhances exercise-induced EDNO synt hesis and aerobic capacity.