Intravascular behavior of a perfluorochemical emulsion.

The purpose of this study was to clarify the reason why two similar perfluorochemical (PFC) emulsions, namely a mixed PFC (perfluorodecalin: FDC and perfluorotripropylamine: FTPA) and an FDC emulsion, resulted in a very different survival time for the exchange-transfused rats. Supposing that some difference in the intravascular behavior of both emulsions would account for such a difference in efficacy, experiments on behavior of PFC emulsions were carried out focusing on the particle size. It was reconfirmed that larger PFC particles were eliminated from the blood stream much more rapidly than smaller particles with three FMIQ (perfluoro-N-methyldecahydroisoquinoline) emulsions. After the FDC + FTPA emulsion or the FDC emulsion were injected into rabbits, PFC particles in the blood tended to decrease in size. When each of the collected blood samples was incubated at 37 degrees C for 24 h, the FDC emulsion enlarged in size markedly, but the FDC + FTPA emulsion showed no change. The retention of PFC particles appeared to depend on the emulsion stability rather than simply on the emulsifying agent alone. These data showed that some differences were observed in intravascular persistence of the FDC + FTPA emulsion and the FDC emulsion, and suggested that the efficacy of PFC emulsions would reflect their behavior in the circulation.