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.

Retention of perfluorochemicals in rat liver and spleen.

The uptake and retention of perfluorochemicals (PFCs) into rat liver and spleen have been measured for up to 28 d following injection of either the commercial PFC emulsion, Fluosol, or a novel perfluorodecalin (FDC)-based emulsion. Both quantitative and qualitative differences in the retention of individual PFCs were observed, depending on composition of emulsion administered. Nevertheless, uptake of PFCs into the spleen was consistently greater than into the liver, irrespective of formulation injected.

Lymphoid tissue responses to concentrated perfluorochemical emulsions in rats.

The effects of injecting perfluorochemical (PFC) emulsions of varying concentrations on lymphoid tissues have been studied in rats. Tissue weights were increased in proportion with quantity of PFC injected, with spleen responses consistently greater than those of the liver. PFC droplets recovered from tissues had mean diameters in the 1-10 microns range, with those from the spleen being larger than from the liver. Recovered droplet diameters were considerably greater than freshly-prepared emulsion mean particle sizes (0.20-0.25 microns). This suggests that coalescence of emulsion droplets following accumulation in tissues is a pre-requisite to the eventual excretion of PFC vapour through the lungs.

Perfluorochemicals and photodynamic therapy in mice.

The effects of pre-treatment with a novel PFC emulsion on PDT-induced tumor necrosis have been studied in mice. Injection of emulsion either 2.5 hr or 24 hr before PDT did not affect the depth of tumour necrosis. However, pre-treatment with the emulsion appeared to protect skin against photodynamic damage although the mechanism(s) and active principle(s) involved were not identified. These results suggest that there may be specific advantages in using emulsified PFCs in conjunction with PDT which may be independent of changes in tumour oxygenation.

Purification of pluronic F-68 for perfluorochemical emulsification.

A novel technique for purification of Pluronic F-68 has been developed involving passage through a silica-Amberlite resin column. Impurities present in commercial grade Pluronic could be readily removed, as confirmed by analysis of absorption and fluorescence emission bands. Intravenous injection of a 4% (w/v) unpurified Pluronic solution in male rats increased mean liver weight by 14% (P less than 0.05) after 24 h and increased spleen weight in female rats by 29% (P less than 0.01) after 7 days. No corresponding tissue weight changes occurred following injection of purified Pluronic solution. Haematocrit and red cell counts were also unchanged throughout. We propose that the use of purified Pluronic for perfluorochemical emulsification may reduce previously reported side-effects.