IDO1 and cardiac arrest: As shown in supplemental figure 7A (https://links.lww.com/ALN/D247), kynurenine levels were significantly increased in plasma after cardiac arrest in IDO−/− mice injected with l-kynurenine compared with naïve IDO−/− mice ([kynurenine] in naïve IDO−/−versus IDO−/−+ l-kynurenine mice 30 min postresuscitation: 41 ± 9 ng/mL versus 5,716 ± 4,157 ng/mL; P = 0.011; n = 4 to 8/group).