Figure 2: 125I-PrPSc levels in whole blood and plasma after p.o. and i.v. administration.
(A) Levels of PrPSc in whole blood and plasma after p.o. administration. Persistently higher levels of 125I-PrPSc in whole blood compared to plasma were observed after p.o. administration. The inset in panel A indicates the time-course of 125I-PrPSc levels after i.v. injection showing similar levels of 125I-PrPSc in the blood and plasma. (B) Blood-to-plasma ratios of 125I-PrPSc representing blood cell association of 125I-PrPSc. While the ratios for 125I-PrPSc after the i.v. injection remained around 1, the ratios after p.o. administration increased with time. Percentages of cell-associated 125I-PrPSc after i.v. and p.o. administration were 14–48%, and 62–87%, respectively. Dashed line represents the ratio of 0.5, which corresponds to the ratio when all material remains in plasma. Blood collected at various time points during the same experiment described in Fig. 1 were separated in plasma and cellular package and radioactivity was quantified and corrected for TCA precipitation. Asterisks indicate statistical difference in the levels between the whole blood and plasma at various time points. Statistical difference was evaluated by two-tailed student T-test with Welch’s correction, and two-way ANOVA followed by the Bonferroni’s test. *P < 0.05, and ***P < 0.001. Mean values with standard error terms are presented. (n = 4–7). ID: Injected dose. Pharmacokinetic parameters for 125I-PrPSc after p.o. and i.v. administrations were calculated by these time-course profiles and summarized in Table 1.
