Fig. 1. Plasma concentrations of total atracurium (A ), unbound atracurium (B ), and α¹-acid glycoprotein (α¹-AGP;C ) and expression of acetylcholine receptor (AchR;D ) at varying periods after infection. Plasma concentrations of total atracurium to maintain 50% neuromuscular paralysis were significantly higher at days 4, 6, and 8 after infection. This requirement returned to normal by days 10–16. The α¹-AGP increased by day 2, peaked at day 4, and gradually returned to normal from days 10 to 16. Expression of AChRs and plasma concentrations of unbound atracurium were unaltered throughout the observation period. *P < 0.05 versus  day 0.