Expression of P-glycoprotein in inner ear capillary endothelial cells of the guinea pig with special reference to blood-inner ear barrier.

Expression of P-glycoprotein (P-gp) was detected immunohistochemically in the guinea pig inner ear using mouse anti-P-gp monoclonal antibody C219. P-gp was found only in the capillary endothelial cells of the cochlea and vestibule. The pattern of P-gp immunostaining in the inner ear was similar to that of the brain. The present investigation suggested that P-gp expression in inner ear capillary endothelial cells might play an important role in the blood-inner ear barrier by acting as an extrusion pump.