[Biomechanical properties study of aorta in β-aminopropionitrile-induced rat model]

To investigate thoracic aortic longitudinal elastic strength in β-aminopropionitrile (BAPN) treated rat model of aortic dissection (AD).

Twenty-nine young rats (Sprague-Dawley) were divided into tow groups, control group (n = 12) and BAPN group (n = 17). Seventeen rats were treated with 0.25% BAPN mixed in feed for 6 weeks. All the rats were sacrificed in the end of experiment and aorta was harvested for biomechanical and pathological study. Longitudinal elastic strength and stress were detected and analyzed by material testing machine. Elasticity modulus as well as maximum stretching length, draw ratio, maximum load, maximum strength, and maximum extensibility was calculated according to the analysis with thickness and area of aortic media.

Nine BAPN-treated rats died of aortic dissecting aneurysm rupture during the experiment. The diameter of the aneurysms was (6.33 ± 1.17) mm and the length was (9 ± 5) mm. The maximum diameter significantly increased in BAPN-induced rats with AD (group B2) compared with without AD (group B1) and control group ((6.49 ± 1.20) mm vs. (1.45 ± 0.11), (1.25 ± 0.26); F = 165.257, P = 0.001 and 0.000, respectively), but there was no significance between group B1 and control group (P = 0.108). Thickness and area of aortic media in BAPN-induced rats significantly increased compared with control group (F = 27.277 and 27.153, P = 0.000 and 0.000, respectively), but there was no significance of area between group B1 and B2 (P = 0.540). Maximum stretching length, draw ratio, maximum load, maximum strength maximum extensibility and elasticity modulus were significantly decreased from group B2, group B1 to control group (P < 0.01, respectively).

This study built a successful model of AD. Biomechanical analysis and the decrease of maximum stretching length, draw ratio, maximum load, maximum strength maximum extensibility and elasticity modulus may explain the formation of AD partly.