Effect of high hydrostatic pressure on the expression of glutamine synthetase in rat retinal Müller cells cultured in vitro.

The aim of the present study was to examine the expression of glutamine synthetase (GS) in rat retinal Müller cells induced by different levels of hydrostatic pressure using a novel pressure mechanism. pH, PCO(2) or PO2 in culture medium as determined by gas analysis was used to examine the pressure mechanism. GS expression in the Müller cells at different levels of hydrostatic pressure (0, 20, 40, 60 and 80 mmHg/24 h) was examined using immunofluorescence, real-time PCR and Western blotting. There was no significant difference in pH, PCO(2) or PO(2) in the culture medium by gas analysis at the different hydrostatic pressure levels (p>0.05). Immunofluorescence staining showed that GS was expressed in the Müller cells. The expression of GS in the 40 mmHg/24 h and the 60 mmHg/24 h groups was increased significantly compared to that in the 0 mmHg/24 h group (p<0.05). These results suggest that the pressure mechanism which was constructed was effective and that moderate pressure promotes the up-regulation of GS in active Müller cells.