Effects Of Endurance Exercise On Cardiovascular Function In Mice

1161 Board #16 3:30 PM – 5:00 PM

PURPOSE

Murine models are central to the current evaluation of cardiovascular and metabolic pathophysiology, often for conditions in which exercise may alter disease progression. However, there are few data on the cardiovascular effects of endurance exercise in mice. We hypothesized that endurance exercise in mice would recapitulate changes similar to the “athletic cardiomyopathy” in man.

METHODS

C57BL/6 mice (n=19) were studied using conscious echocardiography and non-invasive systolic blood pressure (SBP) measurement before and after 3 weeks of voluntary exercise using a recording exercise wheel.

RESULTS

Mice exercised an average of 139±14 min/day (mean±sem, range 30–208 min/day). Average weight did not change. Exercise resulted in a drop in basal ventricular function as reflected in echocardiographic fractional shortening (FS%, 57.9±0.8% to 52.9±1.0%, p < 0.002). Left ventricular wall thickness and diastolic dimension increased modestly after exercise (e.g., LVPWd, 0.095±.004cm to 0.107±.006cm, p=0.02), consistent with an increase in left ventricular mass, but mean heart rate did not change. The change in FS% was not due to increased afterload, since basal systolic BP was decreased after exercise (SBP, 130±5mmHg to 100±6mmHg, p < 0.0004). Left ventricular function augmented with isoproterenol stimulation (to FS% 60.5±0.7%).

CONCLUSION

Endurance exercise in mice results in changes in cardiovascular function that must be considered in evaluating experimental models. These changes can be distinguished from myopathic LV dysfunction by the augmentation of LV function with adrenergic stimulation.