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Mechanisms underlying overshoot dilation after sympathetic denervation.
Blood Vessels
|January 1, 1978
Summary
Sympathetic denervation causes transient femoral vessel dilation, followed by stabilized dilation. Norepinephrine-uptake blockers eliminate the transient phase, suggesting it relates to temporary transmitter reuptake activity.
Area of Science:
- Physiology
- Vascular Biology
- Neuropharmacology
Background:
- Sympathetic nervous system regulates vascular tone.
- Vascular responses to sympathetic denervation are complex.
- Understanding these responses is crucial for cardiovascular research.
Purpose of the Study:
- To investigate the temporal dynamics of femoral artery and vein diameter changes after sympathetic denervation.
- To elucidate the role of norepinephrine reuptake in the observed vascular responses.
- To differentiate between transient and stabilized dilation following sympathetic chain transection.
Main Methods:
- Transection of the sympathetic chain in animal models.
- Measurement of femoral artery and vein diameters over time.
- Administration of norepinephrine-uptake-blocking drugs (cocaine, imipramine).
Main Results:
- A transient 'overshoot dilation' (approx. 120%) occurred within 30-60 seconds post-denervation.
- A subsequent 'stabilized dilation' (approx. 108%) was observed within 5-10 minutes.
- Norepinephrine-uptake blockers abolished the overshoot dilation, yielding only stabilized dilation.
Conclusions:
- Stabilized dilation, not transient overshoot, reflects the loss of sympathetic control.
- Overshoot dilation is attributed to a transient decrease in transmitter concentration with persistent reuptake activity.
- These findings clarify the mechanisms of vascular response to sympathetic denervation.