Dynamic changes of age-related left ventricular hypertrophy found in spontaneously hypertensive rats

Objective To study the dynamic changes of left ventricular hypertrophy with age found in spontaneously hypertensive rats (SHR). Methods Forty-five male SHR and thirty-five male Wistar Kyoto rats (WKY), which were four-week-old and specific-pathogen free, were observed continuously for 42 weeks. At 6,8,12,18,24,32 and 42 weeks of age, cardiac structure and function were examined by echocardiography, and systolic blood pressure was measured by tail cuff method; At the same time points, left ventricular mass index (LVMI) was calculated. The morphology of left ventricle was microscopied by HE staining, genes ANP and β-MHC were detected by RT-qPCR. Results The systolic blood pressure of SHR increased rapidly during the period from 6th to 12th weeks, and was significantly higher than that of WKY at 12 weeks (P＜0.05), after that the blood pressure of SHR increased slightly and slowly. With age and blood pressure changes, left ventricular hypertrophy gradually developed in SHR.The related hypertrophic indexes,interventricular septal thickness(IVST), left ventricular posterior wall thickness(LVPWT),transverse diameter of myocardial cell (TDM) and LVMI all showed characteristic changes. Correspondingly, the expression of hypertrophy-related genes ANP and β-MHC in SHR showed age- and blood pressure-dependent dynamic changes. Conclusions The left ventricular hypertrophy in SHR is characterized by the dynamic changes with aging and change of blood pressure.