Beta carotene decreases total fluorescence from human arteries

The influence of β-carotene content on laser-induced total fluorescence is evaluated in vitro, using human arteries at 488-nm excitation. The investigation demonstrates that the β-carotene content in normal arteries increases with a longer period of incubation in β-carotene solution. This is associated with a decrease in the total fluorescence emission at 488-nm excitation. A decrease of 52% in the total fluorescence emitted from the arterial tissue is noted with the increased β-carotene deposition after incubation. The experimental data are highly correlated with theoretical analyses, derived by using the Kubelka-Munk and Lambert-Beer models, which incorporate parameters of β-carotene content in arterial tissue (r = 0.94 and r = 0.91 , respectively). Total fluorescence from 138 samples of various types of atherosclerotic plaques is compared with that from normal arteries used as controls. Total fluorescence gradually decreases with longer incubation periods in β-carotene solution. For all atherosclerotic plaques, the normalized fluorescence of 0.30 ± 0.16 at initial incubation decreases to 0.23 ± 0.12 after 6 d of incubation (p < 0.005). The value then decreases to 0.19 ± 0.10 after 12 d of incubation (p < 0.005 compared to the initial and 6 d of incubation). Seventy-nine plaques with surface fissures exhibited an accelerated reduction in total fluorescence when compared to nonfissured plaque.