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Increase in plasma beta endorphins precedes vasodepressor syncope
D R Wallbridge1, H E MacIntyre, C E Gray
1Department of Medical Cardiology, Royal Infirmary, Glasgow.
British Heart Journal
|May 1, 1994
Summary
Plasma beta endorphins increase before vasodepressor syncope, indicating a role for endogenous opioids in this condition. This finding was observed during tilt testing in patients experiencing syncope.
Area of Science:
- Neuroscience
- Cardiology
- Endocrinology
Background:
- Endogenous opioids modulate sympathetic tone.
- Opioids are implicated in vasodepressor syncope pathophysiology.
- Plasma beta-endorphin levels rise post-syncope.
Purpose of the Study:
- To assess plasma beta-endorphin levels during tilt testing.
- To determine if beta-endorphin increases before syncope onset.
Main Methods:
- Tilt testing in 24 patients with unexplained syncope.
- Frequent blood sampling for plasma beta-endorphin radioimmunoassay.
- 70-degree head-up tilt protocol.
Main Results:
- Positive tilt tests showed a significant pre-syncope rise in beta-endorphins (4.4 to 8.5 pmol/l, p<0.002).
- Negative tilt tests had no significant change in beta-endorphins.
- All patients exhibited a substantial secondary increase post-syncope (32.3 pmol/l).
Conclusions:
- Elevated plasma beta-endorphins precede vasodepressor syncope.
- This supports a pathophysiological role for endogenous opioids in syncope.