Impaired aerobic capacity in hypercholesterolemic mice: partial reversal by exercise training
Niebauer, J.; Maxwell, A.J.; Lin, P.S.; Tsao, P.S.; Kosek, J.; Bernstein, D.; Cooke, J.P.
American Journal of Physiology 276(4): H1346-H1354
1999
ISSN/ISBN: 0002-9513 PMID: 10199861 Document Number: 499858
The present study assessed whether impaired aerobic capacity previously observed in hypercholesterolemic mice is reversible by exercise training. Seventy-two 8-wk-old female C57BL/6J wild-type (+, n = 42) and apolipoprotein E-deficient (-, n = 30) mice were assigned to the following eight interventions: normal chow, sedentary (E+, n = 17; E-, n = 8) or exercised (Eex+, n = 13; Eex-, n = 7) and high-fat chow sedentary (Echol+, n = 6; Echol-, n = 8) or exercised (Echol-ex+, n = 6, Echol-ex-, n = 7). Mice were trained on a treadmill 2 1 h/day, 6 days/wk, for 4 wk. Cholesterol levels correlated inversely with maximum oxygen uptake (r = -0.35; P < 0.02), which was blunted in all hypercholesterolemic sedentary groups (all P < 0.05). Maximum oxygen uptake improved in all training groups but failed to match Eex+ (all P < 0.05). Vascular reactivity and nitric oxide (NO) synthesis correlated with anaerobic threshold (r = 0.36; P < 0.025) and maximal distance run (r = 0.59; P < 0.007). We conclude that genetically induced hypercholesterolemia impairs aerobic capacity. This adverse impact of hypercholesterolemia on aerobic capacity may be related to its impairment of vascular NO synthesis and/or vascular smooth muscle sensitivity to nitrovasodilators. Aerobic capacity is improved to the same degree by exercise training in normal and genetically hypercholesterolemic mice, although there remains a persistent difference between these groups after training. Reprinted by permission of the publisher.