Abstract:

Abstract:Objective To investigate the electrophysiologic characteristics of volume - sensitive chloride currents in human trabecular meshwork cells and  clarify the relationship between this current and the volume-sensitive chloride channel.Methods Human trabecular meshwork cells were culivated in vitro,whole-cell patch-clamp was used to record the current of chloride channel of human trabecular meshwork cell membrane under the isotonic and hypotonic conditions,and the characteristics of the current and the effects of the chloride channel blockers NPPB and tamoxifen and ATP on the currents under  hypotonic condition were observed.Results Under isotonic condition,only weak and stable background currents were observed;Under  +100 and －100　mV voltage clamp,the outward and inward current density values（pA/pF） were 1.48±0.36 and －0.91±0.10 (n=6), respectively. The currents were increased rapidly by perfusing the cells with hypotonic solution and outward currents were prominent,the outward and inward current density values(pA/pF) were 19.94±0.87 and －0.53±0.41（n=6，P<0.01). When the solution was bathed by chloride channel blockers NPPB(100 mol/L),tamoxifen（50  mol/L）or ATP(2  μmol/L)for 20 min under hypotonic condition,the outward and inward current density values(pA/pF) were 7.61±0.50 and －3.70±0.25,8.21±0.63 and　－3.83±0.25,and 9.08±0.67 and 3.89±0.22, respectively;the outward and inward current density values were reduced significantly than those under  hypotonic condition（P<0.01）.Conclusion The outward chloride currents induced by extracellular  hypotonicity in human trabecular meshwork cells are prominent,which are sensitive to the change of cell volume,and can be inhibited by NPPB,tamoxifen,and ATP.The currents are in line with the characteristics of volume-sensitive chloride currents.

Key words: human trabecular meshwork cell;chloride channels;patch-clamp