Emulsified perfluorochemicals as respiratory gas carriers: recovery of perfluorodecalin emulsion droplets from rat tissues.

To further understand the in-vivo biokinetic behaviour of perfluorochemical (PFC) emulsions, male rats were injected (10 mL kg-1) with 30% (w/v) emulsified perfluorodecalin (FDC) and uptake into tissues assessed. At 72 h after injection, the mean (+/- s.e.m.) diameters of FDC droplets recovered from liver and spleen were 2.24 +/- 0.04 and 2.78 +/- 0.10 microns, respectively; droplets recovered from lung after 72 h (mean: 1.73 +/- 0.13 micron) were significantly smaller (P < 0.01). After 7 days, FDC droplet diameters in liver had increased to 3.31 +/- 0.13 microns (P < 0.01) and those in lung to 2.71 +/- 0.14 microns (P < 0.01); droplets in spleen after 7 days (2.22 +/- 0.09 microns) were similar to those at 72 h. These data support the hypothesis that significant initial coalescence of FDC droplets occurs in the rat liver and spleen, with further coalescence in the liver up to 7 days. The mean percentage of the injected FDC dose recovered from the liver after 72 h was 2.2 +/- 0.4%, and after 7 days was 0.07 +/- 0.05% (P < 0.01). A smaller decrease in the percent injected FDC in spleen also occurred over the same period (72 h: 1.9 +/- 0.3%; 7 days: 0.8 +/- 0.5%; P < 0.01). The percent injected FDC in lung was similar at 72 h (0.007 +/- 0.004%) and 7 days (0.005 +/- 0.001%). FDC was undetectable (< 0.001%) in all blood samples. The greater rate of FDC elimination from the liver than from the spleen may be related to differences in the rates of reticuloendothelial system processing between these organs.