HISTAMINE REDUCES ZO-1 TIGHT-JUNCTION PROTEIN EXPRESSION IN CULTURED RETINAL MICROVASCULAR ENDOTHELIAL-CELLS

We examined ZO-1 protein content in cultured retinal vascular endothel ial cells to test the hypothesis that histamine alters tight-junction- protein expression. Histamine (10(-8)-10(-4) M) causes a reversible co ncentration-dependent reduction of ZO-1 protein content, mediated by b oth H-1 and H-2 receptors. Histamine reduces ZO-1 expression within th e time associated with increased paracellular permeability. Tight-junc tion-protein alterations may be a novel explanation for the mechanism by which vasoactive agents increase microvascular permeability.