Effect of age on peripheral vascular response to transverse aortic banding in mice.

The placement of a ligature to constrict the transverse aorta has become a standard procedure to induce cardiac hypertrophy in mice. Apart from cardiac response, there are adaptive changes in the proximal and distal arterial system that function to maintain adequate peripheral perfusion. The purpose of this study was to characterize the peripheral vascular response by measuring the carotid blood flow using noninvasive Doppler methods, and to investigate the effect of aging on the adequacy and timing of the response after aortic banding in mice. Five 16-month-old and 9 4-month-old male B6D2F1 mice underwent transverse aortic banding. Blood flow velocity was measured with Doppler in the right and left carotid arteries (RCA and LCA) before, 1 day after, and 7 days after, banding. Pulsatility index defined as (peak - minimum)/mean velocity was used to estimate local compliance and distal arterial resistance. The RCA/LCA mean velocity ratio was lower and pulsatility index ratio was higher at 1 day after banding in older mice. However, at 7 days, the RCA/LCA mean velocity ratio and pulsatility index ratio were similar between the 2 age groups. Our data indicate that there is an age-related delay in the development of vascular adaptations in carotid arteries after aortic banding. Older mice take a longer time for adaptation to establish adequate and equal mean flow velocity in the carotid arteries.