Uptake of concentrated perfluorocarbon emulsions into rat lymphoid tissues

The effects of injecting (10-30 mL kg-1) either perfluorodecalin (FDC) emulsions of increasing phase fraction (20-60% w/v) or the commercial formulation, Fluosol, on lymphoid tissues have been studied for up to 7 days in male rats. Tissue weights increased by up to 123% (P < 0.05) in proportion with quantity of perfluorochemical (PFC) injected, with spleen responses consistently greater than those of the liver. PFC droplets recovered from these tissues at 72 h after injection of 30% (w/v) FDC emulsion (10 mL kg-1) had mean diameters in the 1-10 microns range, with those from the spleen being larger than those from the liver. Recovered droplet diameters were considerably greater than freshly-prepared emulsion mean particle sizes (0.21-0.25 microns). These results suggest that coalescence of emulsion droplets following accumulation in lymphoid tissue is a pre-requisite for the eventual excretion of PFC vapour through the lungs.