Fig. 2.

6β-Naltrexol levels across tissues and development. (A) Levels of drug in plasma, brain and liver after a single injection at P7, P14, P20, P32, and P50. E17 and adult (>2 months old) data from Fig. 1 were added for comparison purposes. There is a 45-minute survival time for all data. A break was introduced in the plot to accommodate the extremely high level of drug in P7 liver and to better illustrate the broad range of drug levels across all tissues. Drug levels in most tissues at E17, P7, and P14 are significantly higher than in the corresponding tissues at P20, P35, and P50 (P < 0.05 by t test; not indicated in the figure). Similarly, drug levels in all adult tissues are significantly higher than corresponding tissues at P32 (P < 0.05 by t test; not indicated in the figure). (B) A comparison of drug levels in plasma, brain, and liver at P20 and P32 with two survival times, 20 and 45 minutes. Data for embryonic and adult tissues from Fig. 1 have been added for comparison. The top number on the x-axis is age (days) and the bottom number is survival time (minutes). Asterisks in (A) and (B) indicate plasma vs. brain differences at a particular age; *P < 0.05; **P < 0.01. N = 2 for all samples at P7–P50 (except for plasma at P7, n = 1); for E17 and adults, n is indicated in the Fig. 1 legend.