Emulsified Perfluorochemicals as Respiratory Gas Carriers: Recovery of Perfluorodecalin Emulsion Droplets from Rat Tissues

Abstract

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.

Free Energy Reduction by Molecular Interface Crossing: Novel Mechanism for the Transport of Material Across the Interface of Nanoscale Droplets Induced by Competing Intermolecular Forces for Application in Perfluorocarbon Blood Substitutes

“…PFC liquids injected intravascularly consist of an emulsion of 80-to 500-nm droplets as oxygen carriers. Depending on the route of injection into the body, the journey of the PFC droplets can be distinguished into four subsequent paths: intravascular transport, storage in organs (e.g., liver and spleen), transport to the lungs, and expiration from the alveolae of the lungs [8]. The vascular paths to and from storage organs are characterized by a relatively large distance between particles and a high intravascular mobility of the PFC droplets in comparison to the other paths.…”

“…Two reported mechanisms are thought to be responsible for the increase in drop size: coalescence, which means a fusion of droplets of an emulsion to a compact liquid phase, and Ostwald ripening, known from monocrystal growth in aqueous solutions, by diffusion of molecules from small to larger particles [8,10,12]. Many authors maintain that the observed increase in droplet size most probably occurs in the liver and the spleen, which are organs where the PFCs are trapped for much longer periods than in the blood or lungs [8,10]. While current theories presume that the observed increase in droplet size can be localized in these organs, the proposed models do not offer Fig.…”

“…Two PFC droplets in interfacial contact. Arrow, intact boundary at the zone of contact with respect to organ structure and metabolism [8,10,11]. Below, we introduce a novel mechanism for the transport of material across liquid interfaces induced by competing intermolecular forces which not only describes the changes in droplet size in a high interfacial tension/low miscibility liquid system but also offers a mechanism to understand and possibly influence the expiration rates of PFC droplets in the respiratory system.…”