LASER-INDUCED FLUORESCENCE STUDIES OF THE BIODISTRIBUTION OF CAROTENOPORPHYRINS IN MICE

The biodistribution of two recently developed tumour markers, trimethy lated (CP(Me)(3)) and trimethoxylated (CP(OMe)(3)) carotenoporphyrin, was investigated by means of laser-induced fluorescence (LIF) after i. v. injection into 38 tumour-bearing (MS-2 fibrosarcoma) female Balb/c mice. At 3, 24, 48 or 96 h after administration, the carotenoporphyrin fluorescence was measured in tumoral and peritumoral tissue, as well as in the abdominal, thoracic and cranial cavities. The fluorescence w as induced by a nitrogen laser-pumped dye laser, emitting light at 425 nm, and analysed by a polychromator equipped with an image-intensifie d CCD camera. The fluorescence was evaluated at 490, 655 and 720 nm: t he second and third wavelengths represent the carotenoporphyrin (CP)-r elated peaks, whereas the first one is close to the peak of the tissue autofluorescence. The tumour and the liver were the two tissue types showing the strongest carotenoporphyrin-related fluorescence, whereas the cerebral cortex and muscle consistently exhibited weak substance-r elated fluorescence. In most tissue types, the fluorescence intensitie s decreased over time. A few exceptions were observed, notably the liv er, in which the intensity remained remarkably constant over the time period investigated.