Brain edema in acute arterial hypertension III: fluorescence microscopic results.

Evans blue fluorescence micrographs were investigated from cat brain preparations 5 minutes after angiotensin-induced acute arterial hypertension and intravenous Evans-Blue injection to detect the main localization of Evans-Blue extravasation on the cerebral vasculature. The typical finding was pericapillary and perivenular fluorescence in the cortical grey matter, concentrated in the cytoplasm of neurons. Very intensive staining in the near vicinity of leaking vessels was additionally caused by diffuse fluorescence. The results support the hypothesis that acute arterial hypertension causes critical increase of cerebral venular pressure and venular congestion by overwhelming of cerebral venous outflow-capacity, followed by blood-brain barrier disturbance mainly at the capillaryvenular level.