Comparison between the fluorescence spectroscopy and the¹²⁵I albumin-labeling technique for the study of skin edema dynamics

Abstract

Skin injury caused by chemicals substances as the carrageenan produces a local inflammatory reaction involving the liberation of mediators that leads to an increase in vascular permeability and, consequently, edema formation. The vascular permeability can be evaluated by measuring the amount of some extravasating specific dyes. The Evans blue dye is recommended due to its systemic effect and non-toxicity to the organism. That dye binds to the plasma albumin and emits radiation when excited, allowing for spectroscopic monitoring of the edema. In this study, the amount of extravasating plasma albumin in the site of the carrageenan-induced edema in Wistar rats is evaluated by fluorescence spectroscopy. The intensity of the Evans blue dye fluorescence signal for different edema evolution times is compared to the 125 I labeled albumin data obtained with a γ-counter. A dye laser (458 nm) was used as the fluorescence excitation source. The fluorescence intensity was taken at the 680 nm peak of the dye spectral emission. The spectroscopic data shows the dye emission intensity growing with the settling up of the edema and decreasing as the tissue recovers from the inflammatory stimulus. A good correlation between the spectroscopic and the γ-counter data was obtained, which suggests that the Evans blue dye fluorescence is a promising technique for the qualitative and quantitative analysis of edema dynamics.