Figure 1.

High incidence of AAA formation in C57/B6J mice treated with both AngII and BaP. Representative HE-stained tissue sections of suprarenal segments (1 cm above left renal artery) of the aortas from control and treated mice were shown (A). We measured the circumference of aortic rings from four experimental groups using the computer program of NIH Image J. AAA was defined as circumferences that were increased by more than 50% of the average circumference in the control group (946 ± 69 micrometers). Seven mice from the group treated with both AngII/BaP and two from the AngII-treated group showed AAA formation with circumferences greater than 1417 micrometer (B, each diamond represents a different mouse). Differences in the occurrence of AAA formation between the AngII-treated group and the group treated with both AngII and BaP was statistically significant (P < 0.05). Histology of the aortic wall showed severe damage to the medial layer, breakage of elastic lamella, hematoma, and aortic rupture (indicated by the arrow) in the mouse group treated with both AngII and BaP (A). The aortic wall at the location of rupture was significantly thinner, compared to other parts of the aortic wall. A damaged and thinner aortic wall (broken arrows) was also observed in aortic rings harvested from mice treated with AngII and mice treated with both AngII and BaP.

Abbreviations: AAA, abdominal aortic aneurysm; AngII, angiotensin II; BaP, benzo(a)pyrene; HE, hematoxylin-eosin; NIH, National Institutes of Health.