Aging‐Related Decrease in Bax is Associated with Reduced Susceptibility to ACE Inhibitor‐Induced Remodeling in the Aorta of Spontaneously Hypertensive Rats

Abstract

A 2‐week treatment with angiotensin converting enzyme inhibitor (ACEI) in young adult SHR reverses hyperplasia via apoptosis of aortic smooth muscle cells. The present study examined whether the same effect is observed in older rats. Male SHR (young: 11wks, mature: 26wks) were treated with either tap water or enalapril. Mature rats showed a significant increase in aortic cross‐sectional area, media thickness, lumen diameter, and media to lumen ratio but no change in collagen deposition. Enalapril significantly reduced blood pressure equivalently in young and mature SHR. Aortic medial cell number per unit length was significantly reduced in young, but not mature rats. Expression of pro‐apoptotic protein Bax was significantly reduced in aorta of mature rats. The present study demonstrates that vascular susceptibility to ACEI induced structural remodeling is altered significantly over a relatively short period (15wks) early in adulthood. This may provide a rationale for treating hypertension at an early stage; inasmuch that enhanced vascular remodeling may reduce arterial hypertrophy and stiffening, ultimately leading to improved long‐term protection against hypertensive target organ damage.