Correlation Between Echo-Tracking Parameters and In Vitro Measurements of Arterial Contraction and Relaxation in Rats Fed a High-Cholesterol Diet

BACKGROUND: Echo-tracking (ET) is a new technique that allows the assessment of arterial function and stiffness. This study aimed to ascertain the utility of the echo-tracking (ET) technique to assess vascular stiffness in rats with hypercholesterolemia and atherosclerosis. MATERIAL/METHODS: ET was used to measure the arterial stiffness of the aorta in cholesterol-fed Sprague-Dawley rats (group T1, n=10, for 4 weeks; group T2, n=10, for 12 weeks) and normal control rats (group C1, n=10; group C2, n=10). In vitro isometric tension experiments were used to measure the maximum contractile tension (MCT) and maximum relaxation percentage (MRR%) of aortic rings. Indicators of arterial stiffness and aortic MCT and MRR% were compared between groups using linear regression analysis. Light microscopic evaluation was used to demonstrate atherosclerotic changes in the aorta. RESULTS: The rat models were successfully induced; pathological examination of the aortas showed significant atherosclerosis in group T2, but not in groups C1, C2, or T1. The arterial stiffness parameters obtained using ET and aortic rings in vitro showed significant impairments in T1 and T2 rats compared with C1 and C2 controls (all P<0.05 vs. controls). In addition, these impairments were greater in the T2 group than in the T1 group (all P<0.05). Finally, MRR% correlated with the distensibility coefficient (r=0.396, P=0.012), arterial compliance (r=0.317, P=0.047), stiffness parameter β (r=−0.406, P=0.009) and one-point pulse wave β (r=−0.434, P=0.005). CONCLUSIONS: These results suggest that ET could be used to evaluate the changes in arterial wall elasticity associated with atherosclerosis and hypercholesterolemia.