Related Experiment Videos
The cardiac structure-function relationship and the renin-angiotensin-aldosterone system in hypertension and heart
1Philipps University of Marburg, Germany.
Insights
Arterial hypertension and coronary artery disease contribute to heart failure. Angiotensin converting enzyme (ACE) inhibition can prevent cardiac fibrosis and restore heart function, offering cardioprotective effects.
Area of Science:
- Cardiology
- Cardiovascular Physiology
- Pharmacology
Background:
- Arterial hypertension and coronary artery disease are key factors in heart failure development.
- Heart failure involves regulatory systems like neurohormonal responses and cardiac growth.
- The interplay between neuroendocrine systems and cardiac growth is a significant research area.
Purpose of the Study:
- To investigate the role of the renin-angiotensin-aldosterone system in cardiac structural remodeling.
- To evaluate the cardioprotective effects of angiotensin converting enzyme (ACE) inhibition on myocardial fibrosis and cardiac function.
Main Methods:
- Examined hypertrophic growth in pressure- or volume-overloaded hearts.
- Assessed nonmyocyte cell growth, including cardiac fibroblast activation and vascular smooth muscle cell proliferation.
- Investigated the impact of ACE inhibition (lisinopril) on myocardial structure and function in hypertensive rat models.
Main Results:
- Cardiac fibroblast activation leads to interstitial collagen accumulation and medial thickening of intramyocardial vessels.
- This cardiac remodeling causes myocardial stiffness, impaired vasodilator reserve, and diastolic/systolic dysfunction.
- ACE inhibition demonstrated cardioprotective effects by preventing myocardial fibrosis and restoring cardiac structure and function in rats.
Conclusions:
- The renin-angiotensin-aldosterone system plays a role in the structural remodeling of the nonmyocyte compartment in the heart.
- ACE inhibition offers significant cardioprotective benefits by mitigating cardiac fibrosis and improving cardiac function in hypertensive conditions.
Abstract:
According to the Framingham Study, arterial hypertension and coronary artery disease are the major etiologic factors in the development of heart failure. Regulatory systems that may affect heart failure include the Frank-Starling mechanism, neurohormonal responses, cardiac growth and peripheral oxygen delivery. Recently, the interrelationship between the neuroendocrine system and cardiac growth has aroused much interest. In the pressure- or volume-overloaded heart, hypertrophic growth of the myocardium includes the enlargement of cardiac myocytes, an adaptation governed by ventricular loading. Nonmyocyte cell growth involving cardiac fibroblasts may also occur but is not primarily regulated by the hemodynamic load. Cardiac fibroblast activation is responsible for the accumulation of fibrillar type I and type III collagens within the interstitium and adventitia of intramyocardial coronary arteries, while vascular smooth muscle cell growth accounts for the medial thickening of these vessels. This remodeling of the cardiac interstitium is a major determinant of pathological hypertrophy in that it accounts for abnormal myocardial stiffness and impaired coronary vasodilator reserve, leading to ventricular diastolic and systolic dysfunction and, ultimately, symptomatic heart failure. Several lines of evidence suggest that the renin-angiotensin-aldosterone system is involved in regulating the structural remodeling of the nonmyocyte compartment; this accounts for the cardioprotective effects of angiotensin converting enzyme (ACE) inhibition, which prevents myocardial fibrosis in rats with renovascular hypertension. In rats with genetic hypertension, established left ventricular hypertrophy, abnormal diastolic stiffness due to interstitial fibrosis and reduced coronary vasodilator reserve associated with medial wall thickening of intramyocardial resistance vessels, the ACE inhibitor lisinopril restored myocardial structure and function towards normal.(ABSTRACT TRUNCATED AT 250 WORDS)