Fig. 2

a Microinjection sites mapped on standard sections using the atlas of Paxinos and Watson [16] in 12 Sham and 27 CHF rats. These sites were marked with injected Indian ink after data collection. The areas outlined with thick lines represent the lateral/ventrolateral periaqueductal gray (l/vlPAG). In the l/vlPAG at − 7.8 mm caudal to the bregma for CHF rats, successful microinjection sites of 2 CHF rats were hidden behind the sites presented. b Examples of electrocardiogram tracings obtained from one Sham rat and one CHF rat before and during white noise sound (WNS) exposure. c Thirty-second averaged time courses of mean arterial pressure (MAP) and heart rate (HR) while conscious, free-moving Sham (black circle) and CHF (white circle) rats were exposed to 5 min of WNS at 90 dB 30–40 min after microinjection of saline into the brain, irrespective of microinjection site. Values are mean ± SEM. *P < 0.05, vs. baseline, detected by the Dunnett’s post hoc test following one-way repeated-measures ANOVA. d Comparisons of 5 min averaged changes from baseline in MAP and HR during WNS exposure between Sham and CHF rats. ^†P < 0.05, Sham vs. CHF. NS no significant differences between Sham and CHF rats. The statistic differences were examined by two-sample t tests