Altered left ventricular performance in aging physically active mice with an ankle sprain injury.

Abstract

We assessed the impact of differing physical activity levels throughout the lifespan, using a musculoskeletal injury model, on the age-related changes in left ventricular (LV) parameters in active mice. Forty male mice (CBA/J) were randomly placed into one of three running wheel groups (transected CFL group, transected ATFL/CFL group, SHAM group) or a SHAM Sedentary group (SHAMSED). Before surgery and every 6weeks after surgery, LV parameters were measured under 2.5% isoflurane inhalation. Group effects for daily distance run was significantly greater for the SHAM and lesser for the ATLF/CFL mice (p=0.013) with distance run decreasing with age for all mice (p<0.0001). Beginning at 6months of age, interaction (group × age) was noted with LV posterior wall thickness-to-radius ratios (h/r) where h/r increased with age in the ATFL/CFL and SHAMSED mice while the SHAM and CFL mice exhibited decreased h/r with age (p=0.0002). Passive filling velocity (E wave) was significantly greater in the SHAM mice and lowest for the ATFL/CFL and SHAMSED mice (p<0.0001) beginning at 9months of age. Active filling velocity (A wave) was not different between groups (p=0.10). Passive-to-active filling velocity ratio (E/A ratio) was different between groups (p<0.0001), with higher ratios for the SHAM mice and lower ratios for the ATFL/CFL and SHAMSED mice in response to physical activity beginning at 9months of age. Passive-to-active filling velocity ratio decreased with age (p<0.0001). Regular physical activity throughout the lifespan improved LV structure, passive filling velocity, and E/A ratio by 6 to 9months of age and attenuated any negative alterations throughout the second half of life. The diastolic filling differences were found to be significantly related to the amount of activity performed by 9months and at the end of the lifespan.