Reperfusion effects on the capillary network: an experimental study
Reperfusion during the early stage of cerebral ischaemia reduces infarct size and would be an ideal treatment for this disease. However, experimental studies on ischaemia of the brain have revealed that a transient of the cerebral circulation is followed by an impaired recirculation. The aim of our study was to correlate microangiography with histological and ultrastructural findings in transient forcal cerebral ischaemia. In 32 male Wistar rats, transient focal cerebral ischaemia was induced by endovascular occlusion of the middle cerebral artery (MCA). Twelve animals underwent perfusion fixation for light and electron microscopy while 20 rats were prepared for microangiography. Microangiograms obtained after 2 h of MCA occlusion, and then 2 or 22 h of reperfusion showed a reduction in the number of capillaries. On light and electron microscopy the endothelial cells appeared markedly swollen, resulting in narrowing of the lumina of the capillaries. In this model of transient ischaemia, reperfusion was only partial and a combination of tissue oedema and endothelial swelling caused blockage of the capillaries. Influenced and worsened by other factors, this might be one of the main problems with thrombolytic therapy.
key wordsFocal ischaemia Reperfusion No-reflow phenomenon Microangiography Thrombolysis
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