IL-6 production, Stat3 activation and mortality after PH. Eight to 10 week-old male IL-6 KO or WT mice were subject to 70% PH and then observed for 7 days or sacrificed at different time points. (A) Serum IL-6 levels were measured by ELISA. (B) Phosphorylated-Stat3 (p-Stat3) was measured by western blot. P-Stat3 expression was significantly increased in the liver of WT mice compared to IL-6 KO mice. (C) Animal survival during the 7 days after 70% PH was 100% for WT mice and 17% for IL-6 KO mice. SC injection of IL-6 in KO mice resulted in survival of 67%.