| After establishing that previous methodology was adequate to harvest, store, and culture equine satellite cells (ESC) in vitro, the effects of moderate exercise on ESC were examined. Twelve weanling Quarter Horses were randomly divided into two groups, exercised (EX) and nonexercised (NONEX). EX horses were randomly divided into either a 15 or 30-d exercise regimen, and exercised at a brisk trot (3 m/s) on a high speed treadmill. ESC were obtained by surgical biopsy following treatment periods. Time course studies were used to examine the main effects of exercise on proliferation and differentiation of ESC in vitro.;There were no differences between proliferation and differentiation of EX and NONEX treatments. There was a day effect on percent fusion (P $<$.001), and on total nuclei per/mm$sp2$ (P $<$.0001) on d 1, 3 and 5 of cultures from weanlings running the 15-d protocol. Similarly, there was a day effect (P $<$.01) on proliferation at all time periods between nonexercised horses and horses on the 30-d protocol.;The ability of serum from exercised or nonexercised horses to effect proliferation or differentiation of equine satellite cells in vitro was examined. During d 3 and 5 in culture, serum from exercised weanling horses increased (P $$.10) between serum types. There was a tendency (P $<$.07) for an increase in total cell density in cultures treated with serum from exercised weanling horses on d 1. From d 3 through 7, ESC cultured in exercised serum had greater (P $<$.001) percent fusion than cells cultured in serum from nonexercised weanling horses. There were no treatment differences between satellite cell cultures originating from exercised and nonexercised weanling horses. However, there was a significant day of culture, serum, and day of culture by serum increase for both proliferation and differentiation. When comparing proliferation of ESC treated with NONEX and EX serum from weanling horses, there was a significant (P $<$.0001) serum by day of culture interaction. There was a serum by day of culture interaction on d 3 (P $<$.001) and d 5 (P $<$.004), with a tendency (P $<$.07) for interaction on d 1, and no difference (P =.36) on d 7. |
