Fig. 3

Heart rate viability alterations in rabbits with different treatment at different time after HCl-induced acute lung injury. a, alterations of LF/HF ratio in different groups; b alterations of LF in different groups; c alterations of HF in different groups. For control group (n = 8), rabbits only received saline intratracheally injection (2.8 ml/kg) after surgery; for HCl groups (n = 8), ALI model was established by intratracheal injection of HCl (pH 1.5, 2.8 ml/kg); for VNS groups (n = 8), after the ALI model established by HCl, rabbits also received constant voltage stimuli (5 V, 2 ms, and 1 Hz); for THA group (n = 8), after ALI model established by HCl, rabbits also received THA (3 mg/kg) intravenous injection; and for SGB group, after ALI model established by HCl, rabbits also continuously received 0.25% bupivacaine pumping via epidural catheter (3 mg/kg). LF, low frequency; HF, high frequency; VNS, vagus nerve stimulation; THA, tetrahydroaminoacridine; SGB, stellate ganglion block; ALI, acute lung injury