Fig. 1. (A ) Time course of uptake of fluorescence-labeled lipopolysaccharide (LPS) in beating rat hearts. Surface fluorescence is recorded at 589 nm using excitation light of 524 nm. Data are expressed as increase in fluorescence light ± SD as compared with fluorescence light intensity after 2-min perfusion with Texas Red LPS. Logarithmic regression, R²= 0.99. (B ) Intracellular uptake of fluorescent LPS assessed in intact perfused rat hearts. Hearts were perfused for 8.5 min with fluorescent LPS followed by 21.5-min washout with LPS-free perfusate. Values were expressed a percentage of the peak fluorescence, and the mean values of four experiments were fitted to a polynomial regression (R²= 0.87). All measurements have been adjusted for background autofluorescence.