The purpose of this study was to investigate the age-related changes in diastolic filling parameters in the aging hearts of active C57Bl/6J mice throughout the life span to indicate optimal age periods for improvements in resting diastolic parameters.Methods
Fourteen C57Bl/6J mice (seven males and seven females) were individually housed at 8 wk of age in cages with a running wheel, magnetic sensor, and digital odometer. Duration, distance, and running velocity were recorded daily. Fourteen additional mice C57Bl/6J mice (seven males and seven females) were placed in individual cages without running wheels at 8 wk of age. Pulsed-wave Doppler transmitral inflow recordings with a SONOS 5500 ultrasound and 15-6L ultrasound probe were used to image the left ventricle every 4 wk throughout the life span.Results
Peak E wave filling velocities were significantly greater by the start of the second quarter of the life span in the mice with access to running wheels (P < 0.0001). Peak E wave velocities improved in both groups during the first half of the life span (P < 0.0001) and declined throughout the second half of the life span (P < 0.0001). Early-to-late (E:A) filling ratio was significantly greater for the physically active mice by the start of the second quarter of the life span (P < 0.0001) and continued throughout most of the remainder of the life span (P < 0.0001). No differences were observed between the two groups of mice with peak A wave filling velocities (P > 0.05). Similar findings were observed when corrected for resting heart rate.Conclusions
Lifelong physical activity resulted in greater diastolic filling parameters by the second quarter of the life span, highlighting the clinical importance of regular aerobic activity in young adulthood as a mechanism for improved left ventricular performance with aging.