Figure 3:

Panel A: Change in heart rate just prior to the onset of Valsalva to phase III release before (baseline) and during autonomic blockade in HFpEF, senior and young controls. After autonomic blockade, all groups demonstrated blunted (<10 bpm) rise in heart rate signifying decreased cardiac parasympathetic activity. Panel B: Plasma norepinephrine (NE) levels during isoproterenol infusion. HFpEF patients had higher baseline NE levels compared to young and senior controls (418 ± 223 vs 231 ± 75 vs 200 ± 101 pg/ml; p = 0.009) but had similar relative drop after blockade (p = 0.74). NE levels remained steady for all groups (p = 0.88) during ISO infusion reflecting stable and persistent withdrawal of sympathetic noradrenergic outflows. Both young and senior controls had NE levels below 100 pg/ml after autonomic blockade, consistent with sympathetic withdrawal. Error bars are standard error of mean.