Mechanism of Gender-Specific Differences in Aortic Stiffness With Aging in Nonhuman Primates

Abstract

Background— Our hypothesis was that the changes in vascular properties responsible for aortic stiffness with aging would be greater in old male monkeys than old female monkeys. Methods and Results— We analyzed the effects of gender differences in aging on in vivo measurements of aortic pressure and diameter and on extracellular matrix of the thoracic aorta in young adult (age, 6.6±0.5 years) versus old adult (age, 21.2±0.2 years) monkeys ( Macaca fascicularis ). Aortic stiffness, as represented by the pressure strain elastic modulus (Ep), increased more in old male monkeys (5.08±0.81; P P P Conclusions— There are major species differences in the effects of aging on aortic collagen types 1 and 3. Furthermore, because alterations in collagen density, collagen content, hydroxyproline, and collagen advanced glycation end products were similar in both old male and female monkeys, these factors cannot be responsible for the greater increase in stiffness in old males. However, changes in collagen isoforms and the decrease in elastin observed only in old males likely account for the greater increase in aortic stiffness.