Abstract 240: Serum Cholesterol and Angiotensin-Induced Abdominal Aortic Aneurysm in Hypercholesterolemic Mice

Abstract

Background Although hyperlipidemia is known to augment the incidence of abdominal aortic aneurysms (AAA) in the AngII-induced model of apolipoprotein E -/- mice, its relationship to AAA size is unknown. Therefore, we evaluated the relationship between total cholesterol concentration (TC) and change (delta) in aortic diameter. Methods TC was measured in 36 male mice that underwent a 4-week infusion period with saline (n=9) or AngII (1500 ng/kg/min; n=27), along with serial measurements of pulse rate (PR), and pulse (PP), mean arterial (MAP), systolic (SBP) and diastolic (DBP) pressure. A linear mixed effect model was used to assess the relationship between all hemodynamic parameters and delta. Nonparametric and linear regression methods were used to evaluate TC in relation to delta. Results TC did not differ between AngII and control mice (Figure, bottom left) (p=0.18). The burden of atherosclerosis was greater among AngII-exposed mice versus control, but did not differ by presence or size of AAA (Figure, bottom right). None of the hemodynamic parameters were predictive of delta (SBP, p = 0.66; DBP, p = 0.66; MAP, p = 0.55; PP, p = 0.66; and PR, p = 0.39). Mean TC was higher among mice with large versus small AAA (552.6 vs. 393.5 mg/ ml, p<0.05; Figure, top right). The nonparametric smoothing line (Figure, top left) suggests a first order relationship between delta and TC (p for trend < 0.001). AngII (ß = 0.48, p < 0.001) and TC (ß = 0.0015, p = 0.003) were independent predictors in the linear model for delta. Conclusions Our findings suggest that TC is incrementally associated with AAA size. These findings may have potential clinical relevance for risk assessment in AAA patients. Figure