Supplemental nitric oxide augments satellite cell activity on cultured myofibers from aged mice

Betters JL, Lira VA, Soltow QA, Drenning JA, Criswell DS.
Center for Exercise Science, Department of Applied Physiology & Kinesiology, University of Florida, P.O. Box 118206, Gainesville, FL 32611, USA.

Skeletal muscle regenerative potential is reduced with aging. We hypothesized that in vitro activation of muscle satellite cells would be compromised, and that nitric oxide (NO) supplementation would improve satellite cell activity in old muscle. Single intact myofibers were isolated from the gastrocnemius muscles of young (2mo), adult (10mo), and aged (22mo) mice. Fibers were centrifuged to stimulate satellite cells and incubated with a NO donor or control media for 48h. The number of activated satellite cells after centrifugation was reduced in aged fibers compared to young and adult. NO treatment increased satellite cell activation in all age groups. However, an age-dependent deficit in satellite cell activity persisted within treatment groups. In separate fibers, exogenous HGF was equally effective in activating satellite cells across age groups, indicating that events downstream of HGF release are intact in aged muscle. These data suggest that NO production limit muscle satellite cell activity in response to a submaximal mechanical stimulus, regardless of age. Further, the decline in satellite cell activity in early senescence can be partially abrogated by a NO donor.