The Disposition and Bioavailability of 35 S-GSH from 35 S-GSSG in BSS PLUS ® in Rabbit Ocular Tissues

Abstract

The purpose of this study was to evaluate the biodistribution and uptake of ³⁵S-GSH into intraocular tissues following the administration of BSS PLUS^® containing ³⁵S-GSSG by either an anterior chamber or intravitreal injection. This study evaluated the disposition and uptake of the ³⁵S-radiolabel, the intracellular concentrations of ³⁵S-GSH from extracellular ³⁵S-GSSG, and the percentage of ³⁵S-GSH to the total cellular GSH pool. Glutathione was analyzed by high-performance liquid chromatography (HPLC) using fluorescence detection after derivitizing the thiols in situ with monobromobimane. The effluent from the GSH peak was then collected for measurement of ³⁵S-GSH. After an anterior chamber injection of ³⁵S-BSS PLUS, ³⁵S-radioactivity rapidly disappeared from the aqueous humor between 0.5 and 2 hours; corneal ³⁵S-radioactivity remained constant over time. ³⁵S-GSH was detected in the iris and ciliary body. However, in the cornea, ³⁵S-GSH became the predominant radioactive thiol in the stroma, endothelium, and epithelium; the corneal stroma appeared to be a possible GSH reservoir for the adjacent corneal layers. After an intravitreal injection, ³⁵S-radioactivity slowly decreased in the vitreous humor but was readily taken up by the tissues of the posterior segment, especially the retina and choroid, which showed the greatest concentrations of ³⁵S-GSH of all tissues studied. The data from this study demonstrate that ³⁵S-GSSG in BSS PLUS is metabolized and taken up by ocular cells and that ³⁵S-GSH becomes incorporated into the intracellular GSH pool of ocular tissues.