Origin and localization of Evans blue extravasations in acutely-induced hypertension in cats

An intravital-microscopic study on cat pial vessels for the localization of Evans blue extravasation during acute hypertension was performed. The onset of extravasation was seen 10 sec to 2 min after the beginning of hypertension. The localization of initial extravasation turned out to be little venules, not arterioles. Venular congestion by an overload of venous outflow seemed to be the origin of extravasation.