Abstract
Purpose: :
The use of donor lenses for antioxidant research may be problematic due to biochemical changes induced by storage for longer periods of time. The aim of the study was to examine the time dependent effect of post mortem conditions on the concentration of glutathione and the ratio between oxidized and reduced glutathione using the rat as a model.
Methods: :
Sprague Dawley rat lenses were surgically removed immediately after death. The lenses were stored in two different media, Optisol-GS and castor oil, for varying time periods ranging from 1 hour to 72 hours. They were homogenized on ice and stored at -80 ºC until analysis could be performed. Glutathione and GSSG were determined with the Promega GSH-Glo assay.
Results: :
Lenses stored in both Optisol-GS and castor oil demonstrated a rapid decline in the concentration of glutathione within the first 24 hours after death. The concentration of glutathione in lenses stored in Optisol-GS decreased 89,2% within the first 24 hours whereas the concentration of glutathione in lenses stored in castor oil only decreased 59,1% during the first 24 hours. For the remainder of the observational period glutathione slowly declined an additional 4,9% for Optisol-GS and 8,9% for castor oil. The ratio between reduced and oxidized glutathione also declined rapidly. From an initial value of 8,2 to average values of 1,7 for Optisol and 2.0 for castor oil after 24 hours. Afterwards the ratio in both media remained constant throughout the observational period.
Conclusions: :
Lenses stored in Optisol-GS showed a rapid and significant decline in the concentration of glutathione due to leakage into the surrounding medium. This leakage was much slower in castor oil which has a lower affinity for the polar structure of glutathione due to its high content of fatty acid, thus serving to prevent transport of glutathione into the medium.