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Sympathetic nervous system during converting enzyme inhibition.
1Department of Medicine, Prince of Wales Hospital, Chinese University of Hong Kong, Shatin, New Territories.
The American Journal of Medicine
|December 26, 1989
Summary
Angiotensin-converting enzyme (ACE) inhibitors show minimal impact on sympathetic activity in most humans but may suppress it in severe heart failure. These drugs appear to enhance parasympathetic activity, potentially aiding their hemodynamic effects.
Area of Science:
- Cardiovascular Pharmacology
- Autonomic Nervous System Physiology
Background:
- Angiotensin II influences sympathetic and parasympathetic nervous system activity.
- Angiotensin-converting enzyme (ACE) inhibitors block Angiotensin II formation.
- Expected effects of ACE inhibitors include reduced sympathetic and enhanced parasympathetic activity.
Purpose of the Study:
- To investigate the effects of ACE inhibitors on sympathetic and parasympathetic activity in humans.
- To clarify the impact of ACE inhibitors in normotensive, hypertensive individuals, and those with cardiac failure.
Main Methods:
- Analysis of existing evidence, primarily from measurements of venous norepinephrine levels.
- Indirect assessment of autonomic nervous system activity due to limitations in direct recording techniques.
Main Results:
- ACE inhibitors demonstrate little to no effect on sympathetic activity in normotensive and hypertensive humans.
- Evidence suggests ACE inhibitors may suppress the activated sympathetic system in severe cardiac failure.
- ACE inhibitors appear to exert a parasympathomimetic action.
Conclusions:
- ACE inhibitors may have a parasympathomimetic effect contributing to their hemodynamic benefits.
- Further research using direct sympathetic recordings or norepinephrine spillover is needed to fully elucidate ACE inhibitor effects on the sympathetic system.