Comparative Effects of Angiotensin II Type 1 Receptor Blockade with Angiotensin-Converting -Enzyme Inhibitor on Aortic Smooth Muscle Cell Phenotype in Spontaneously Hypertensive Rats

To clarify the effects of renin-angiotensin system inhibition on aortic smooth muscle cell phennotype and fibrosis in spontaneously hypertensive rats (SHR), we treated 14-week -old SHR with a selective angiotensin II type 1 (AT1) receptor blockade, FK-739 (30mg/kg day) or sngiotensin-converting-enzyme (ACE) inhibitor, enalapril (10mg/kg/day) for 6 weeks. Both FK-739 and enalapril caused a significant decrease in blood pressere (p < 0.001) with no difference between the treated groups. Immunoblot showed no significant decrease in the expression of smooth muscle cell myosin heavy chain and nonmuscle myosin heavy chain (NMHC)-A in SHR aorta. In contrast, both FK- 739 and enalapril resulted in s significant decrease in the expression of NMHC-B compared with vehicle (vehicle vs FK-739 treated group

Angiotensin II type 1 receptor blockade

Smooth muscle celｌ

Myosin heavy chain isoform

Fibrosis

Hypertension