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[Hemodynamic adaptations in proximal cerebrovascular occlusion]
1Laboratorium voor Normale en Pathologische Fysiologie, Rijksuniversiteit Gent.
Verhandelingen - Koninklijke Academie Voor Geneeskunde Van Belgie
|January 1, 1990
Summary
Investigating carotid occlusion in rats revealed that while resting brain blood flow recovers quickly, the cerebrovascular reserve, crucial for adapting to changes like hypercapnia, takes longer to restore, especially in hypertensive rats. This highlights the importance of CO2 reactivity as a measure of brain blood flow reserve post-stroke.
Area of Science:
- Neuroscience
- Physiology
- Vascular Biology
Background:
- Extracerebral cerebrovascular occlusion, such as carotid artery blockage, significantly impacts cerebral hemodynamics.
- Understanding the brain's compensatory mechanisms and reserve capacity following such events is crucial for managing cerebrovascular diseases.
- Hypertension can exacerbate the negative effects of carotid occlusion due to pre-existing vascular abnormalities.
Purpose of the Study:
- To investigate the cerebral hemodynamic behavior after unilateral or bilateral carotid artery occlusion.
- To assess the recovery of resting brain blood flow and cerebrovascular reserve capacity over time.
- To compare the hemodynamic responses in normotensive and spontaneously hypertensive rats (SHR).
Main Methods:
- Acute unilateral and bilateral common carotid artery occlusion in Wistar rats and Spontaneously Hypertensive Rats (SHR).
- Measurement of hemispheric brain blood flow under resting conditions and during hypercapnia.
- Assessment of cerebrovascular reserve using CO2 reactivity.
- Evaluation of survival rates after consecutive bilateral carotid occlusions with varying intervals.
Main Results:
- Unilateral carotid occlusion moderately lowered resting brain blood flow, with faster recovery of resting flow than cerebrovascular reserve.
- Cerebrovascular reserve, indicated by hypercapnic blood flow increase, showed slower recovery, reaching near-normal levels by day 30.
- SHR exhibited impaired adaptation and poorer survival rates compared to normotensive rats, with hemodynamic compensation lagging significantly.
- Acute bilateral carotid occlusion in cats reduced resting cerebral blood flow in anterior brain regions while preserving posterior regions.
Conclusions:
- Restoration of resting cerebral blood flow is rapid, but the recovery of cerebrovascular reserve capacity is a slower process.
- Spontaneously Hypertensive Rats demonstrate a reduced ability to adapt to carotid occlusion, underscoring the impact of hypertension on cerebrovascular resilience.
- CO2 reactivity serves as a reliable indicator of cerebrovascular reserve following occlusive events, correlating with survival rates after bilateral occlusion.