Abstract:

Abstract:Objective
To analyze the influence of dexamethasone in the hypotonic-induced volume-sensitive chloride currents in human trabecular meshwork cells,and to investigate the possible mechanism of volume-sensitive chloride channels(VACC) in the glucocorticoid-induced glaucoma(GIG) cases.Methods The human trabecular meshwork cells were seeded in 35 mm diameter plastic petri dishes,so that they could grow in monolayer.The cultured cells were divided into  normal cell culture medium group and dexamethasone 1 d,3 d,7 d groups.The  chlorine current density values of the cells in four groups were recorded respectively by the whole-cell patch-clamp technique.The differences among groups were compared.Results In normal group,after hypotonic stimulation,under +100 and -100 mV voltage clamp,the outward and inward current density values of the trabecular cells were (19.94±0.87) and (－6.53±0.41)　pA/pF.In dexamethasone 1 d,3 d， and 7　d groups,under  the same condition,the outward and inward current density values of the trabecular cells were  (19.39±1.40) and (－6.42±0.28)　pA/pF,(17.97±2.35) and (－5.82±0.94)　pA/pF,(17.16±1.16) and (－5.65±0.43)　pA/pF.The trabecular cells cultured with dexamethasone for 1 d  had lower outward and inward current density values under hypotonic stimulation compared with normal group,but there was no significant difference (P>0.05).The trabecular cells cultured with dexamethasone for 3 d and 7 d,when compared with normal group,had significantly lower outward and inward current density values under hypotonic stimulation (P<0.05).Conclusion Dexamethasone could reduce the volume-sensitive chloride current in trabecular meshwork cells,which would affect trabecular meshwork cell volume adjustment.This would possibly cause the increase of the aqueous humor outflow resistance among GIG cases.

Key words: trabecular meshwork cells, chloride channel, patch, clamp technique, dexamethasone