When blood pressure changes, Angiotensin II is produced and released into the bloodstream. This substance can make blood vessels smaller (i.e., vasoconstriction) by acting through Angiotensin II type I receptors (AT1R) to increase blood pressure. Or it can increase the diameter of vessels (i.e., vasodilation) through Angiotensin II type II receptors (AT2R) to decrease blood pressure. These two receptors normally work in balance to maintain blood pressure. However, excess Angiotensin II released in the bloodstream may reduce the sensitivity of AT2Rs, leading to excessive activation of AT1Rs. This results in increased constriction which plays a major role in diseases such as high blood pressure, hardening of the arteries, and heart failure. In the body, Angiotensin II production is reduced in the presence of estrogen, as seen in pre-menopausal women. Pre-menopausal women have a greater protection against cardiovascular diseases compared to age-matched males, likely due to the protective effects of estrogen. However, the extent that estrogen may impact the sensitivity of Angiotensin II receptors in pre-menopausal is unknown.
In this study, the investigators use the blood vessels in the skin as a representative vascular bed for examining mechanisms of microvascular dysfunction in humans. Using a minimally invasive technique (intradermal microdialysis for the local delivery of pharmaceutical agents), the blood vessels in a dime-sized area of the skin are studied in healthy young women and men. As a compliment to these measurements, blood is drawn from the subjects and circulating factors that may contribute to cardiovascular health are measured.
The safety and scientific validity of this study is the responsibility of the study sponsor and investigators. By listing a study does not mean it has been evaluated by the U.S. Federal Government. Know the risks and potential benefits of clinical studies and talk to your health care provider before participating. Read our disclaimer for details.