The renin-angiotensin-aldosterone system in pre-eclampsia

Area of Science:

• Obstetrics and Gynecology
• Cardiovascular Physiology
• Endocrinology

Background:

• Pre-eclampsia presents with plasma volume contraction, intravascular coagulation, and vasoconstriction.
• The renin-angiotensin-aldosterone (RAA) system's role in pre-eclampsia is complex, deviating from initial hypotheses of overactivity.

Purpose of the Study:

• To investigate the specific alterations in the renin-angiotensin-aldosterone (RAA) system components and their functional implications in pre-eclampsia.
• To explore the relationship between RAA system changes and the clinical severity of pre-eclampsia.

Main Methods:

• Measurement of plasma renin activity (PRA), renin concentration (PRC), angiotensin II (AII), and aldosterone concentrations (PAC) in pre-eclamptic and normal pregnancies.
• Assessment of RAA system component responses to physiological stimuli, such as frusemide.
• Evaluation of pressor sensitivity to infused AII and the plasma active renin to prorenin ratio.

Main Results:

• Plasma renin activity, angiotensin II, and aldosterone concentrations are reduced in pre-eclampsia compared to normal pregnancy.
• Despite reduced AII levels, there is heightened pressor sensitivity to AII in pre-eclampsia.
• The plasma aldosterone concentration to renin concentration ratio is elevated, and an inverse relationship exists between the active renin to prorenin ratio and clinical severity.

Conclusions:

• The renin-angiotensin-aldosterone system is significantly altered, not overactive, in pre-eclampsia, characterized by reduced activity but increased sensitivity to angiotensin II.
• These RAA system modifications, including heightened adrenal sensitivity to AII, are crucial aspects of pre-eclampsia pathophysiology.
• Further understanding of these mechanisms provides critical insights into the overall pathogenesis of pre-eclampsia.