Effects of ovariectomy and estrogen replacement on aorta angiotensin-converting enzyme activity in rats.

We investigated the possibility that physiological doses of estrogen protect against atherosclerotic change produced by changes in vascular angiotensin-converting enzyme (ACE) activity. Rats were ovariectomized, and after 14 days, treated with estradiol-17 beta (0.2 microgram/rat) for 14 weeks. Aorta ACE activity significantly increased in the ovariectomized rats, and decreased following estradiol-17 beta administration to a level not different from proestrous control rats. These results suggest that the lack of estrogenic action increases atherosclerotic change associated with changes in aorta ACE activity and that estrogen replacement therapy reduces the risk of atherosclerotic change associated with the decrease of aorta ACE activity.