1998 Volume 8 Issue 5 Pages 516-520
The expression of P-glycoprotein (P-gp), a membrane-bound drug efflux pump for many anti-cancer drugs in multidrug-resistant cells, in endothelial cells of capillary blood vessels of the cochlea in mice was investigated.
The cochlea of the FVB mouse was decalcified in 10% EDTA solution (pH7.4) for 4 days. After embedding in OCT compounds (Miles, USA), the cochlea was cut on a cryostat into 12μm sections. Sections were fixed in cold acetone, then incubated with mouse anti-P-gp monoclonal antibody C219 (Centocor, USA) overnight at 4°. A peroxidase-conjugated goat anti-mouse IgG (Dako, Denmark) was applied for 1h at room temperature. As negative control, the sections were similarly immunostained except that the primary antibody was replaced with PBS. Sections from the brain were used as positive control.
P-gp was found only in the capillary endothelial cells of cochlear tissue. Tissues or cells other than capillary blood vessels were not stained. In the cochlea, positive-staining was observed in the stria vascularis, spiral ligament, spiral limbus, basilar membrane, spiral ganglion, and cochlear nerve in the modiolus, but not in the bony capsule. Immunoreactivity in the cochlea was similar to that in the brain.
The present investigation suggests that P-gp expression in the capillary endothelial cells of the cochlea might play an important role in the blood-inner ear barrier.
