Biochemical opening of the blood-brain barrier

Biochemical agents that can influence the abnormal BBB are reviewed. Vasoactive compounds, including leukotrienes, bradykinin, histamine appear to selectively increase permeability in abnormal brain capillaries. Normal brain capillaries resist the effects of these compounds through an 'enzymatic barrier' that may inactivate vasoactive agents. In contrast, this enzymatic barrier is lost in certain diseased states, allowing vasoactive compounds to selectively increase permeability in abnormal capillaries. Clinically, intracarotid infusion of leukotrienes, bradykinin and other vasoactive agents can increase drug delivery to diseased tissue.