Figure 2.

Time course and dose response of FAM-NP41 binding to nerve and nonnerve tissue. (a–d) Nerve fluorescence peaked at around 10 min after administration (a), then declined (half-life ~50 min) to a plateau sustained between 3 and 6 h (see inset with expanded intensity scale, Student’s t-test, two–tailed, P = 0.002 at 2 h, 0.0007 at 3 h, 0.0007 at 4 h, 0.003 at 5 h, 0.006 at 6 h). In contrast, muscle fluorescence was highest immediately after intravenous administration of the peptide, then declined steadily with a half-life of ~20 min (a). Serum half-life was calculated at ~10 min (b). Useful contrast between nerve and surrounding muscle developed by 2 h and lasts several hours (c). Nerve-to–surrounding tissue contrast ratio increased with increasing amount of peptide injected, concentration from 15 to 5,000 nmoles per mouse injected (n = 2) (d), because surrounding nonnerve tissue fluorescence seems more saturable than nerve binding with increasing peptide concentration (inset).