Endothelium-dependent changes in arterial diameter in old normotensive rats

Area of Science:

• Vascular biology
• Gerontology
• Cardiovascular physiology

Background:

• Endothelial function is vital for regulating arterial diameter and stiffness.
• Previous studies showed endothelium removal increases arterial diameter in young rats.
• The role of endothelial function in arterial stiffness in aged rats remains under-investigated.

Purpose of the Study:

• To assess the contribution of endothelial function to arterial stiffness regulation in aged rats.
• To compare endothelial-dependent vasodilation in young versus aged rats.
• To investigate age-related changes in carotid artery structure and function.

Main Methods:

• Isobaric carotid diameter was measured in vitro in situ in young (10-month) and aged (30-month) normotensive female WAG/Rij rats.
• Measurements were taken under baseline conditions, after endothelium removal, and after smooth muscle relaxation with potassium cyanide.
• High-resolution echotracking and histomorphometry were used to assess arterial diameter and wall structure.

Main Results:

• Aged rats exhibited increased carotid artery wall thickness and collagen content compared to younger rats.
• While potassium cyanide caused a slight increase in diameter in aged rats, endothelium removal did not.
• Endothelium-dependent increases in isobaric carotid diameter were significantly blunted in aged rats.

Conclusions:

• Endothelial function is impaired in aged rats, leading to blunted endothelium-dependent vasodilation.
• Altered endothelial function may contribute to age-dependent increases in arterial stiffness.
• These findings highlight the importance of endothelial health in aging vasculature.