Fig. 3

Brief hypoxemic ischemia challenges reveal changes in sympatho-respiratory response in relation to peripheral infection. Representative recordings of perfusion pressure (PP), integrated thoracic sympathetic chain (tSNA), vagal (VNA) and phrenic (PNA) nerve activity from sham control (A black traces) and E. coli-infected preparations (B red traces) before and after brief hypoxemic ischemia, mimicked by stopping the perfusion pump for 20 s. Compared to sham controls, we observed a decrease in the strength of the initial hypoxemic ischemia respiratory augmentation (C lower number of respiratory cycles with TTOT shorter than TTOT at baseline before stopping the pump in the E. coli group); a significantly less pronounced post-hypoxic frequency decline (D lower number of respiratory cycles with TTOT longer than TTOT at baseline before stopping the pump in the E. coli group) accompanied by significantly enhanced integrated tSNA (E)