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Atropine does not attenuate cerebral vasodilatation during hypercapnia
The American Journal of Physiology
|April 1, 1982
Summary
Cholinergic nerves do not significantly contribute to cerebral vasodilation during hypercapnia. Blocking muscarinic receptors with atropine did not alter blood flow increases in the brain under elevated carbon dioxide levels.
Area of Science:
- Neuroscience
- Cardiovascular Physiology
Background:
- Cholinergic nerves are implicated in regulating cerebral blood flow (CBF).
- The role of cholinergic nerves in cerebral vasodilation during hypercapnia remains unclear.
Purpose of the Study:
- To investigate the contribution of cholinergic nerves to cerebral vasodilation during hypercapnia.
- To determine if muscarinic receptor blockade affects CBF responses to hypercapnia.
Main Methods:
- Anesthetized cats underwent measurements of total and regional CBF using microspheres.
- Muscarinic receptors were blocked with atropine (0.5 mg/kg) intravenously.
- Cranial window technique assessed atropine's efficacy and specificity on pial artery dilation.
Main Results:
- Hypercapnia induced dose-dependent increases in CBF across all brain regions.
- Atropine administration did not attenuate the CBF increases observed during hypercapnia.
- Atropine effectively blocked acetylcholine-induced vasodilation but not adenosine-induced vasodilation.
Conclusions:
- Cholinergic nerves do not appear to play a significant role in steady-state cerebral vasodilation during hypercapnia.
- The study suggests that muscarinic receptors are not the primary mediators of hypercapnia-induced cerebral vasodilation.