Angiotensin II Induces Cardiac Phenotypic Modulation and Remodeling In Vivo in Rats

Abstract

Cardiac phenotypic modulation and remodeling appear to be involved in the pathophysiology of cardiac hypertrophy and heart failure. We undertook this study to examine whether angiotensin II (Ang II) in vivo, independent of blood pressure, contributes to cardiac phenotypic modulation and remodeling. A low dose (200 ng/kg per minute) of Ang II was continuously infused into rats by osmotic minipump for 24 hours or 3 or 7 days to examine the effects on the expression of cardiac phenotype–related or fibrosis-related genes. This Ang II dose caused a small and gradual increase in blood pressure over 7 days. Left ventricular mRNAs for skeletal α-actin, β-myosin heavy chain, atrial natriuretic polypeptide, and fibronectin were already increased by 6.9-, 1.8-, 4.8-, and 1.5-fold, respectively, after 24 hours of Ang II infusion and by 6.9-, 3.3-, 7.5-, and 2.5-fold, respectively, after 3 days, whereas ventricular α-myosin heavy chain and smooth muscle α-actin mRNAs were not significantly altered by Ang II i...