Comparison study of AngII induced cardiac hypertrophy model in TR3+/+ and TR3-/- mice by echocardiography

Objective To compare of the thickness of left ventricular wall of Ang Ⅱ induced cardiac hypertrophy model in both TR3 konock-out C57BL/6 mice (TR3-/- mice) and wild type C57BL/6 mice (TR3+/+ mice) by high frequency ultrasound,combined with experimental research to discuss if TR3 take part in the process of cardiac hypertrophy.Methods 26 TR3 -/- mice and 33 TR3 +/+ mice were randomized to 2 groups respectively:TR3+/+ + AngⅡ group (27 mice),TR3+/+ + PBS group(6 mice),TR3-/- + Ang Ⅱ group(20 mice),TR3-/- + PBS group(6 mice).Micro-pumps with AngⅡ or PBS were placed into the subcutaneous tissue of mice to construct hypertension model in 4 weeks.Interventricular septum enddiastolic thickness (IVSd) and left ventricular posterior wall end-diastolic thickness (LVPWd) were measured by echocardiography 2 days before operation and every week after operation until 4 weeks.Then,mice were killed and mice cardiomyocytes were isolated and detected in lab (HE dyeing test,Western blotting).Results ①Echocardiography:before operation,IVSd and LVPWd was not statistically different between TR3+/+ group and TR3-/- group( P ＞0.05).1 - 2 weeks after operation,IVSd and LVPWd had peaked in both TR3-/- + Ang Ⅱ group and TR3 +/+ + Ang Ⅱ group,IVSd and LVPWd in TR3 +/+ + Ang Ⅱgroup were significantly thicker than control group (TR3 +/+ + PBS group) ( P ＜0.05),IVSd and LVPWd in TR3-/- + AngⅡ group were slightly thicker than control group (TR3-/- + PBS group) ( P ＜0.05).Compared with TR3-/- + Ang Ⅱ group,IVSd and LVPWd in TR3+/+ + Ang Ⅱ group were markedly increased( P ＜0.05).After 4 weeks operation,IVSd and LVPWd of all 4 groups were not statistically different than that in the 2nd week.②HE dyeing test:The cell size of cardiomyocytes in TR3+/+ mice increased significantly after Ang Ⅱ treatment,while TR3-/- mice did not.③ Western blotting:Ang Ⅱ promoted TR3 expressions in TR3 +/+ mice( P ＜0.05).Conclusions TR3 do take part in the process of Ang Ⅱ induced cardiac hypertrophy in mice and it is a key factor in this process. Key words: Echocardiography; Hypertension; Myocardial hypertrophy; Angiotensin Ⅱ ; TR3