Pathophysiology of the blood-retinal barrier in experimental diabetes. Vitreous fluorophotometry using carboxyfluorescein and fluorescein
N. P. Blair, C. W. Jones and M. M. Rusin
Carboxyfluorescein resembles fluorescein in size and spectral
characteristics but is much less lipid soluble. Both dyes were used to
differentiate between two groups of factors that influence penetration
across the blood-retinal barrier: (1) factors that depend on lipid
solubility, such as the area of the barrier, and (2) factors independent of
lipid solubility, such as opened intercellular junctions or necrotic cells.
Vitreous fluorophotometry was performed on normal and diabetic rats after
injection of either dye. After the results were adjusted for sources of
error, midvitreous-plasma dye ratios for carboxyfluorescein and fluorescein
were of the same order of magnitude in normal rats. Ratios for both dyes
increased in diabetic rats, and the increases were similar in magnitude.
Our results suggest that lipid solubility contributes little to inward
transport of these dyes in both the normal and diabetic states.
