Abstract 15411: Effects of Age and Gender on Murine Thoracic Aortic Mechanical Properties
Background: Inherent characteristics of the thoracic aorta (TA), including passive (extracellular matrix: ECM) and active (smooth muscle cell contraction) tension, provide the mechanical compliance to support the high hemodynamic force generated during the cardiac cycle. Because cardiovascular disease risk is modified by age and gender, it is expected that the structural and cellular composition of the aorta is also modified by age and gender. Accordingly, the goal of this study was to determine the effects of age and gender on the passive and active tension of the TA.
Methods/Results: TA rings (3mm, n=2-3 per aorta) were harvested from young (6 months; male (n=3), female (=3)) and old (21 months; male (n=3), female (=3)) C57BL/6 mice. To determine the TA passive tension, aortic segments were denuded of endothelium and subjected to isometric force transduction in a tissue bath, by sequentially increasing applied tension by 0.1 g increments under physiologic conditions. The active component was determined in TA segments over a range of applied tension, by stimulating contraction with potassium chloride (100μM). Results demonstrated that peak passive tension in young male mice (0.56±0.03 g) was significantly lower than in old male mice (1.03±0.06 g; p<0.05), while passive tension was similar between young (1.00±0.12 g) and old (0.96±0.13 g; p=NS) females (Figure ). Young aortas (149±26 mg) generated higher contractile tension (64±22 mg) than old aortas, however no gender effect was observed.
Conclusion: This study demonstrated that a physiologically relevant change in the mechanical properties of the murine TA occurs with aging, including an increase in passive tension and a loss of contractile ability. Furthermore, there was age-related difference in ECM composition by gender. Together, these data demonstrate that TA compliance is altered by age and gender, and suggest that these changes may affect the risk of developing aortic disease, such as TA aneurysm.
- © 2013 by American Heart Association, Inc.