Angiotensin II likely plays limited role in menopause-related hypertension

Angiotensin II likely plays limited role in menopause-related hypertension

Hypertension-November 17, 2003

According to published research from Canada, "Activation of the renin-angiotensin system has been implicated in the development of hypertension in menopausal women."

D. Javeshghani and coauthors at the Clinical Research Institute of Montreal "investigated whether blood pressure is elevated and whether angiotensin II (Ang II)-induced vascular reactivity is increased in follitropin receptor knockout (FORKO) female mice."

"These mice are estrogen-deficient and have characteristics similar to postmenopausal women," they explained in the journal Hypertension.

"Serum estradiol levels were significantly reduced in FORKO versus wild-type mice (1.4ą0.2 versus 15ą3 pg/mL, p<0.01)," study data revealed. "Blood pressure, measured by telemetry, was significantly increased in FORKO (120ą2/92ą2 mm Hg) compared with their wild-type counterparts (110ą1/85ą2 mm Hg, p<0.05)."

"Vascular dose responses to acetylcholine (endothelium-dependent dilation) and sodium nitroprusside (endothelium-independent dilation) were not different. Ang II-induced vasoconstriction was blunted in FORKO compared with wild-type mice (p<0.05)," according to the report. "Media-to-lumen ratio was significantly increased in FORKO (6.2%ą0.5%) versus control mice (5.2%ą0.3%), indicating vascular remodeling."

"Aortic * O2- levels, NADH-inducible O2- generation, and plasma levels of thiobarbituric acid reactive substances (TBARS), indexes of oxidative stress, were not significantly different between wild-type and FORKO mice. Vascular AT1 receptor content, assessed by immunoblotting, was reduced by 40% in FORKO compared with wild-type mice (p<0.01). This was associated with decreased circulating Ang II levels in FORKO versus control mice," test results revealed. "These data indicate that FORKO mice have increased blood pressure, vascular remodeling, and attenuated vascular responses to Ang II."

"Our findings suggest that vascular Ang II signaling is downregulated in female FORKO mice and that Ang II may not play an important role in blood pressure elevation in this model of menopause-associated hypertension," the researchers concluded.

Javeshghani and colleagues published their study in Hypertension (Attenuated responses to angiotensin II in follitropin receptor knockout mice, a model of menopause-associated hypertension. Hypertension, 2003;42(4 Part 2):761-767).

For additional information, contact R.M. Touyz, Clinical Research Institute of Montreal, Experimental Hypertension Research Laboratory, 110 Pine Avenue West, Montreal, PQ H2W 1R7, Canada.

Publisher contact information for the journal Hypertension is: Lippincott Williams & Wilkins, 530 Walnut St., Philadelphia, PA 19106-3621, USA.

The information in this article comes under the major subject areas of Endocrinology, Hypertension and Women's Health. This article was prepared by Health & Medicine Week editors from staff and other reports.