1346 Title: Does the lens of the eye possess a coordinated volume regulatory system?

pumoSe The purpose of this study was to investigate the role of Clchannel) in lens volume regulation and its involvement in cataractogenesis. There is considerable evidence that lens swelling precedes opacification. The primary role of the lens is to focus light onto the retina and a prerequisite for achieving this is to maintain lens transparency Questions therefore to be addressed arej how can the lens maintain its special ptrysiological strxture and do the lens fibre cells need a regulatory system to keep their volume constant? Ma (1) Vesicles were formed thorn posterior bovine lens fibre cells and used for “cell-attached” patch clamping (2) The viable fibre cells containing nuclei were plated onto a coverslip coated with cooling agar. (3) Digital images of lenses were taken at intervals with a CCD camera and the anteriorposterior (A-P) and equatorial diameters were measured R& When the lens tibre cell vesicle:; were exposed to 30% hypotonic solution single Clchannel activity (g=lSpS) increased in vesicle-attached patches Additionally, hypotonic solution induced an outwardly rectifying current in whole-cell recordings from posterior fibre cells, which reversed at the chloride equilibrium potential and was reversibly inhibited by chloride channel blockers (e.g NPPB and tamoxifen). When whole bovine lenses werb exposed to 50% hypotonic solution the lens A-P diameter returned to a value near its control level after an initial swell. This phenomenon was inhibited by chloride channel blockers. Conck~~sions We conclude that the lens fibre cells possess volume-activated Clchannels. A strong connection between these channels and lens swelling i6 indicated and their inhibition results in lens opacification, raising the possibilitv of a volume regulatory system involved in maintaining lens structure