In vivo fluorescence kinetics of porphyrins following intravesical instillation of 5-aminolaevulinic acid in normal and tumour-bearing rat bladders

Abstract

The fluorescence kinetics of photoporphyrin IX (PPIX) following intravesical instillation of 5-aminolaevulinic acid (5-ALA) have been studied in vivo in a rat bladder tumour model. 5-ALA dissolved in NaHCO 3 was intravesically instilled for 60 min in tumour-bearing and normal bladders of Wistar rats. The fluorescence was excited with the violet lines of a Kr +-laser and recorded in vivo by means of a fibre coupled optical multichannel analyser. The fluorescence emission bands of PPIX at λ = 636 nm and λ = 708 nm were detected in normal and tumorous orothelium after only 30 min. The maximum fluorescence intensity was obtained in tumorous and normal urothelium 3–4 h after instillation. The ratio of the fluorescence intensity in tumorous to normal urothelium decreased continuously from four to about two during the time range of 6 h. PPIX fluorescence following 5-ALA installation could also be observed in kidney and liver. Fluorescence from further porphyrin species with emission bands at λ = 617 nm and λ = 682 nm was detected in the bladder, indicating an efflux of hydrophilic porphyrins from the hepatic pathway.