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Blood flow through cerebral collateral vessels one month after middle cerebral artery occlusion
Abstract:
Acute occlusion of a middle cerebral artery (MCA) reduces cerebral blood flow in normotensive Wistar-Kyoto rats (WKY) and in stroke-prone spontaneously hypertensive rats (SHRSP). The goal of this study was to determine whether MCA occlusion produces a sustained reduction in cerebral blood flow or whether collateral vessels restore blood flow to normal levels. We measured blood flow through cerebral collateral vessels to the territory of the occluded MCA and to homologous tissue of the other hemisphere in WKY 1 month after occlusion of the MCA. Cerebral blood flow, measured with microspheres, was restored to normal levels under control conditions in the territory of the occluded MCA. During vasodilatation produced by seizures, blood flow and vascular conductance were increased to similar levels in tissue distal to the site of MCA occlusion and in the homologous tissue of the other hemisphere. MCA occlusion did not produce infarction in any of the WKY. In contrast, 1 month after MCA occlusion in SHRSP, a large atrophic infarct was invariably present in the territory of the occluded MCA. The number of collateral vessels to the territory of the MCA do not differ in SHRSP and WKY. Internal diameter and orientation of the anastomotic vessels differ in SHRSP and WKY. We conclude that, after 1 month of MCA occlusion, changes in the collateral vessels supplying the territory of the occluded MCA in WKY were sufficient to restore blood flow to normal under control conditions and to virtually normal levels during vasodilatation.(ABSTRACT TRUNCATED AT 250 WORDS)
Insights
Middle cerebral artery (MCA) occlusion in Wistar-Kyoto rats (WKY) allows collateral vessels to restore normal cerebral blood flow. However, stroke-prone spontaneously hypertensive rats (SHRSP) develop infarcts after MCA occlusion due to differing collateral vessel characteristics.
Area of Science:
- Neuroscience
- Cerebrovascular Research
- Animal Models of Stroke
Background:
- Middle cerebral artery (MCA) occlusion is a common model for studying stroke.
- Understanding the role of collateral circulation is crucial for stroke recovery.
- Differences in blood pressure and vascular health can impact stroke outcomes.
Purpose of the Study:
- To investigate if collateral vessels restore cerebral blood flow after MCA occlusion.
- To compare the effects of MCA occlusion in normotensive WKY rats and hypertensive SHRSP rats.
- To determine if MCA occlusion leads to sustained blood flow reduction or infarction.
Main Methods:
- MCA occlusion was performed in WKY and SHRSP rats.
- Cerebral blood flow was measured using microspheres.
- Blood flow and vascular conductance were assessed under control and seizure-induced vasodilatation conditions.
- Histological analysis was performed to detect infarction.
Main Results:
- In WKY rats, cerebral blood flow was restored to normal levels 1 month after MCA occlusion.
- During vasodilatation, blood flow and vascular conductance increased similarly in occluded and homologous tissues in WKY rats.
- MCA occlusion did not cause infarction in WKY rats, but SHRSP rats invariably developed infarcts.
- Collateral vessel numbers were similar, but internal diameter and orientation differed between WKY and SHRSP rats.
Conclusions:
- Collateral vessel adaptations in WKY rats effectively restore cerebral blood flow after MCA occlusion.
- Differences in collateral vessel structure contribute to the development of infarction in SHRSP rats.
- Vascular health significantly influences the brain's response to arterial occlusion and the efficacy of collateral compensation.