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Increased cerebral infarction by cyclic flow reductions: studies in the guinea pig MCA thrombosis model
1Department of Pharmacology, Hamamatsu University School of Medicine, Hamamatsu 431-3192, Japan.
Abstract:
We have developed a photochemical model of thrombotic middle cerebral artery (MCA) occlusion in the guinea pig for investigating factors contributing to the development of cerebral infarction. In this model, cyclic flow reductions (CFRs) after recanalization of the MCA are a common observation and might contribute to the development of cerebral infarction. Therefore, we sought to measure the time course of recanalization of the guinea pig MCA after the artery had been occluded by a thrombus. Thrombotic occlusion of the MCA was induced by photochemical reaction between intravenously administered rose bengal and transluminal green light for 10, 15, 20, or 30 min. After the thrombotic occlusion of MCA and subsequent spontaneous thrombolysis, blood flow in the MCA gradually recovered to preocclusion level but with frequent CFRs. The recovery of MCA blood flow or duration of CFRs was dependent on the duration of photochemical reaction (extent of endothelial injury); thus, for a 30-min photochemical reaction, CFRs were still observed 24 h after photochemical reaction. In separate experiments, we also investigated the effect of permanent occlusion of the MCA, which was induced by electrocoagulation in the vessel on cerebral infarction. The infarct volume in the permanent occlusion model was smaller than the maximum value in the thrombotic occlusion model (12.5 vs. 17.4%; P < 0.05, n = 6). CFRs may constitute an important factor contributing to the extent of cerebral infarction.
Insights
Researchers created a guinea pig model for middle cerebral artery (MCA) occlusion to study stroke. Cyclic flow reductions (CFRs) following recanalization were observed, potentially increasing cerebral infarction extent.
Area of Science:
- Neuroscience
- Vascular Biology
- Pathophysiology
Background:
- Cerebral infarction is a significant cause of neurological disability.
- Thrombotic occlusion of the middle cerebral artery (MCA) is a common stroke mechanism.
- Understanding factors contributing to cerebral infarction is crucial for developing effective treatments.
Purpose of the Study:
- To develop and characterize a photochemical model of thrombotic MCA occlusion in guinea pigs.
- To investigate the time course of MCA recanalization and cyclic flow reductions (CFRs) after occlusion.
- To compare infarct volumes between thrombotic and permanent MCA occlusion models.
Main Methods:
- Thrombotic MCA occlusion induced by rose bengal and green light photochemistry (10-30 min).
- Measurement of MCA blood flow and observation of CFRs post-recanalization.
- Induction of permanent MCA occlusion via electrocoagulation for comparison.
Main Results:
- Spontaneous recanalization of the MCA occurred with frequent CFRs after thrombotic occlusion.
- The duration of photochemical reaction influenced MCA blood flow recovery and CFRs.
- Infarct volume was larger in the thrombotic occlusion model compared to permanent occlusion (17.4% vs. 12.5%).
Conclusions:
- The developed photochemical model effectively mimics thrombotic MCA occlusion and subsequent recanalization with CFRs.
- CFRs following MCA recanalization may play a significant role in determining the extent of cerebral infarction.
- This model provides a valuable tool for investigating stroke pathophysiology and therapeutic interventions.