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Angiotensin II: vasoconstrictor or growth factor?
1Department of Medicine, University Hospital of South Manchester, England.
Insights
Sustained high blood pressure causes heart and blood vessel structural changes. Angiotensin II may promote vascular growth independently of blood pressure, impacting cardiovascular risk.
Area of Science:
- Cardiovascular Physiology
- Vascular Biology
- Hypertension Research
Background:
- Sustained hypertension leads to adaptive structural changes in the heart and vasculature.
- Left ventricular hypertrophy is a significant predictor of cardiovascular events, potentially more so than blood pressure itself.
- The precise changes in resistance vessels due to hypertension remain unclear.
Purpose of the Study:
- To investigate the cellular mechanisms underlying structural alterations in the circulation during hypertension.
- To explore the role of pressor hormones, specifically angiotensin II, as growth factors in vascular tissues.
- To examine the pressure-independent actions of angiotensin II on vascular growth.
Main Methods:
- Review of recent studies on cellular mechanisms in hypertension-induced vascular remodeling.
- Analysis of in vitro and in vivo evidence regarding angiotensin II's role in vascular growth.
- Examination of signaling pathways activated by angiotensin II in vascular cells.
Main Results:
- Left ventricular hypertrophy and changes in major arteries are established consequences of hypertension.
- Evidence suggests angiotensin II can promote vascular tissue growth through mechanisms independent of direct pressure effects.
- Angiotensin II's non-pressor actions are implicated in in vitro and in vivo vascular remodeling.
Conclusions:
- Hypertension-induced vascular structural changes are complex and involve more than just mechanical pressure.
- Angiotensin II possesses growth-promoting properties in vascular tissues that are not solely dependent on elevated blood pressure.
- Understanding these cellular mechanisms is crucial for developing targeted therapies for hypertensive cardiovascular disease.
Abstract:
The consequence of a sustained rise in blood pressure is an adaptive change in the structure of the heart and the vasculature. In humans, the left ventricle, aorta, and medium-sized arteries undergo hypertrophy whereas the changes in resistance vessels are unclear at present. Recent studies suggest that left ventricular hypertrophy is a better predictor of stroke or cardiac risk than age or blood pressure. Therefore, the cellular mechanisms that bring about these structural alterations to the circulation in hypertension are the subject of intense research at this time. The main factor was assumed to be the pressure load imposed on the wall of the left ventricle and the arteries. However, recent work has suggested that pressor hormones can act as growth factors in vascular tissues by pressure-independent actions. This article examines the cellular mechanisms activated by angiotensin II that could be involved in producing growth and the evidence available that this nonpressor role is important in vitro and in vivo.