Increasing muscle mass improves vascular function in obese (db/db) mice.
Bottom Line: Inactivity is associated with a loss of muscle mass, which is also reversed with isometric exercise training.This impairment was improved by superoxide dismutase mimic Tempol.This improvement was blunted by nitric oxide (NO) synthase inhibitor l-NG-nitroarginine methyl ester (l-NAME).
Affiliation: Vascular Biology Center and Department of Physiology, Georgia Regents University, Augusta, GA, Germany (S.Q., J.D.M., C.D.S., W.H., A.G., F.C., Y.Y., Y.S., D.J.F., D.W.S.).Show MeSH
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Mentions: The effect of myostatin on muscle mass is depicted in Figure 3 in a number of ways. In Figure 3A, lower‐limb muscles from cadaver mice are shown for the purpose of illustration. Limb mass was observably larger after myostatin deletion than those of lean and obese control mice. Figure 3B shows the axial T1‐weighted cross‐section of the lower‐limb muscles by MRI in anesthetized mice. Obese mice showed a decreased cross‐section area of lower‐limb muscles, whereas deletion of myostatin increased muscles in both lean and obese mice. For Figure 3D, individual muscles were dissected free and weighed for quantitative assessment. Deletion of myostatin significantly increased tibialis anterior (TA) in both lean and db/db mice, essentially restoring obese muscle mass back to lean levels. Similar results were observed in the gastrocnemius (GS), gluteal, and triceps muscles (Table 3). To determine the anatomic basis of increased muscle mass, TA muscle fiber size was assessed histologically with H&E‐stained cryosections (representative examples in Figure 3C) as well as as box and whisker plots comprising minimum, median, and maximum value for muscle fiber diameter (Figure 3E). Obese mice showed decreased TA muscle fiber size, compared to lean mice (28.52±0.25 vs. 43.29±1.01 μm; P<0.05), deletion of myostatin increased TA muscle fiber size in both lean and db/db mice (lean myostatin−/−: 50.06±1.02 μm; db/db myostatin−/−: 46.08±0.96 μm; P<0.05).
Affiliation: Vascular Biology Center and Department of Physiology, Georgia Regents University, Augusta, GA, Germany (S.Q., J.D.M., C.D.S., W.H., A.G., F.C., Y.Y., Y.S., D.J.F., D.W.S.).