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Prazosin depression of baroreflex function in hypertensive man
European Journal of Clinical Pharmacology
|January 1, 1982
Summary
Prazosin effectively lowers blood pressure in hypertensive patients without increasing sympathetic activity. This study found prazosin reduces baroreflex sensitivity, potentially explaining the lack of reflex sympathetic response.
Area of Science:
- Cardiovascular Pharmacology
- Autonomic Nervous System Physiology
Background:
- Prazosin is an alpha-adrenergic blocker used for hypertension.
- Its hypotensive effect is not associated with increased sympathetic activity or reflex tachycardia.
Purpose of the Study:
- To investigate the baroreceptor reflex arc as a mediator of prazosin's unique hypotensive effects.
- To determine if prazosin alters sympathetic nervous system activity or baroreflex sensitivity.
Main Methods:
- A randomized controlled trial comparing prazosin to placebo in 22 essential hypertensive men.
- Measurements included blood pressure, heart rate, plasma renin activity, sympathetic nervous system markers, and baroreflex sensitivity.
Main Results:
- Prazosin significantly reduced blood pressure without altering heart rate or sympathetic activity markers.
- Baroreflex arc sensitivity was significantly depressed by prazosin treatment.
- No significant change in cardiac vagal inhibition was observed.
Conclusions:
- Prazosin's ability to lower blood pressure without sympathetic activation may be partly due to a depression of baroreflex arc sensitivity.
- This finding offers insight into the mechanism of prazosin's therapeutic action in hypertension.