Osmotically induced increase in cerebrovascular permeability to [3H]sucrose

The effect of an intracarotid infusion of a 5 M urea solution on the blood--brain barrier of the rat was measured using the carotid injection technique. The urea infusion increased the amount of sucrose penetrating the barrier. This increased uptake of sucrose was first seen 10--25 sec after the 15 sec urea infusion. By 10 min, sucrose uptake had decreased in some animals.