Cerebrovascular permeability in stroke-prone spontaneously hypertensive rats

Cerebrovascular permeability in the stroke-prone strain of spontaneously hypertensive (SHR) rats drinking a 1% NaCl solution was examined by injection of Evan's blue, or ¹²⁵I-labeled human serum albumin (¹²⁵I-HSA), before and immediately after the onset of stroke. Leakage of Evan's blue was locally found in the brain or spinal cord from rats with stroke signs, but not in those from rats without the signs. Examination of serial sections of the blue areas revealed association of dye leakage with pathological changes such as medial thickening and fibrinoid degeneration of arterioles, petechial hemorrhage, and edema. The increased cerebrovascular permeability to ¹²⁵I-HSA was observed only in the blue spot areas but not in other parts of brain even in the rats with stroke signs. These findings indicate that increased cerebrovascular permeability is limited to the focal area with small vascular lesions which are closely related to the onset of stroke.