Dilation and reduced distensibility of rat carotid artery with aging

To better understand the pathogenesis of increased arterial stiffening with aging, the relative contribution of geometry (lumen diameter) and stiffening of wall components (elastic modulus) to reduced distensibility of rat carotid artery in the early stages of aging was investigated. Pressure-volume (distensibility) relationships were measured in excised, in vitro perfused right carotid artery of 7-. 10- and 20-month old, male Sprague-Dawley rats. The left carotid artery of rats was perfusion-fixed in situ at 100 mm Hg and then embedded in epoxy for morphometric measurements. Compared to 7- and 10-month old rats, there was dilation (increased lumen diameter), increased wall thickness, and reduced distensibility and unchanged elastic moduli of carotid artery in 20-month old rats. Dilation (with early recruitment of collagen fibrils during pressure rise) rather than increased stiffness of wall components appears to be the cause of reduced distensibility of rat carotid artery in the early stages of aging.