OBJECTIVETo perform an initial study on possible molecular regulatory mechanisms of TNF-alpha to the permeability of strial capillary endothelial cells in guinea pig cochlea

METHODSStrial capillary endothelial cells in guinea pig cochlea was dissociated and cultured to establish a model for its permeability in vitro. The animals were divided into TNF-alpha, TNF-alpha + L-arginine (L-Arg), TNF-alpha + NG-monomethyl-L-arginine (L-NMMA) and control groups. In order to measure the alternations of permeation rate, Evans blue was used in different time by different concentrations to detect contents of F-actin in each group under immunofluorescence laser scanning confocal microscope.

RESULTSTNF-alpha increased permeability of strial capillary endothelial cells notably, and permeation rate to Evans blue heightened significantly (P < 0.01) and increased under higher concentrations of TNF-alpha as well as lengthened the durations. Being as a NO donator, L-Arg significantly enhanced the ability of TNF-alpha which increasing permeability of strial capillary endothelial cells; permeation rate to Evans blue heightened significantly (P < 0.01), which obviously rose up when the concentration of Evans blue added. L-NMMA, NO inhibitor, was able to weaken the ability of TNF-alpha which increasing permeability of strial capillary endothelial cells; permeation rate to Evans blue decreased significantly (P < 0.01), which obviously fell down when the concentration of L-NMMA added. TNF-alpha decreased F-actin in strial capillary endothelial cells (P < 0.01), more TNF-alpha, less F-actin; L-Arg could be further the inhibition to F-actin content (P < 0.05); L-NMMA held back the trend (P < 0.05).

CONCLUSIONSTNF-alpha can increase permeability of strial capillary endothelial cells of guinea pig cochlea. NO may be one of the important molecular regulators to permeability of strial capillary endothelial cells by TNF-alpha, and changes of F-actin content probably relate to the regulation in these cells.