The Research Related Mechanism Of Angiotensin Ⅱ During Formation Of Aortic Dissection In Mice

Objective To explore the formative mechanism of dissection of aortainduced by Angiotensin II.Method Forty C57BL/6J mice, healthy and8months old were randomly dividedinto2groups, experimental group and control group each made up of20mice.Mice of experimental group received Angiotensin II4.5mg/kg/day withintraperitoneal injection while those of control group receivednoradrenaline12mg/kg/day with intraperitoneal injection. Thirty minutesafter injection, their blood pressure levels were measured using tail cuffblood pressure device to keep the general balance, and the entire procedurelasted for14days. Fourteen days later, the arteriae aorta walls were takento observe their structure through pathology. Meanwhile, the level ofmatrix metalloproteinase-9(MMP-9), matrix metalloproteinase-2(MMP-2) andmetalloprotease tissue inhibiting factor-2(TIMP-2) was tested byimmunohistochemical method. The average optical expressed by MMP-9, MMP-2and TIMP-2between the two groups was measured by computer image analyticaltechnique.Result1Level of blood pressure in experimental group was134.5±3.5mmHg,versus （132.9±2.7） mmHg in control group, showing nosignificance difference between them (P>0.05).2Among20mice in experimental group, the tunica media ofarteriae aorta walls of12mice were found thinner and some ofthem were broken.Also,7mice were found with obvious aortic dissection versus no significant change in control group.3The level of MMP-9and MMP-2in experimental group wassignifcantly higher than control group (P<0.05) while TIMP-2was significantly lower than control group (P<0.05).Conclusion ANG-Ⅱ induced mice’s aortic dissection by increasing thelevel and activity of MMP-9, MMP-2and lowering that of TIMP-2.