FIGURE 3.

Countermeasures against halogen toxicity. Post-Cl₂ administration of antioxidants increase survival Mice were exposed to 600 ppm of Cl₂ for 45 min and returned to room air. A: they received intramuscular injections of ascorbate (Asc; 2 mg) and deferoxamine (Desf; 0.3 mg) in saline starting at 1 h after exposure and every 12 h thereafter up to 60 h after exposure. They also received aerosols of ascorbate (150 mg/mL) and deferoxamine (0.3577 mg/mL) at 1.5, 24, and 48 h after exposure in sterile water. Control mice received vehicle (saline for intramuscular injections; sterile water for aerosols) instead of antioxidants using identical protocols. Data points were fitted with Kaplan-Meier survival curves and compared with the log-rank test (P = 0.0007) (from Ref. 41). B: post-Br₂ exposure administration of hemopexin increases survival. C57BL/6 mice were exposed to Br₂ (400 ppm for 30 min) and returned to room air. At either 1 h or 5 days post-exposure they were given a single intraperitoneal injection of purified human hemopexin (Hx) (4 µg/g body wt) or vehicle. Survival was assessed in the next 14 days. The Kaplan-Meier curve demonstrated that Hx reduced mortality after Br₂ exposure, even when was given 5 days later. *P < 0.05 vs. Br₂ + saline by one-way ANOVA followed by Tukey’s post hoc test (68). C: post-Br₂ administration of tadalafil (Cialis; TDF or TAD) decreases mortality of pregnant (P) mice. Nonpregnant (NP) and P gestational day 14.5 (E14.5) mice were exposed to air or to Br₂ at 600 ppm for 30 min and returned to room air; they received tadalafil (TAD; 2 mg/kg body weight in 0.1 mL of sterile saline) or vehicle via oral gavage at 1 h post-exposure and every 24 h thereafter. Data show Kaplan-Meyer curves of P and NP mice with tadalafil or vehicle, post-Br₂ exposure. NP mice exposed to Br₂ and returned to room air lived longer than similarly exposed P mice (*P < 0.05) (from Ref. 55). D: post-Cl₂ administration of nitrite improves survival. Male or female mice were exposed to Cl₂ at 600 ppm, 45 min and then brought back to room air, and nitrite was administered by intramuscular injection 30 min post-exposure. Data show Kaplan-Meier survival curves. P < 0.03 between male and female Cl₂-alone groups; P < 0.02 for nitrite therapy in males and P = 0.09 for nitrite therapy in females.