Does an acute inflammatory response temporarily attenuate parasympathetic reactivation?

Purpose Although observational studies suggest that inflammatory markers are associated with autonomic nervous system function, the causal relationship of this is not clear. We tested the hypothesis that acute inflammation will temporarily attenuate vagal reactivation as measured by heart rate recovery after exercise. Methods In this double-blind randomized study, 24 healthy subjects were assigned to receive either an influenza vaccine (n = 15) as a model to generate a systemic inflammatory response or a sham vaccine (n = 9). Heart rate recovery after exercise testing was used as an index of parasympathetic nervous function and was calculated as the difference between maximal heart rate during the test and heart rate 1 and 2 min after cessation of exercise. Both blood analysis and treadmill exercise stress tests were conducted before and 48 h after each vaccination. Results Inflammatory marker, log C-reactive protein (1.9 ± 1.2 to 2.8 ± 1.4, (p<0.05) was significantly increased after the influenza vaccine. Heart rate recovery 1 was significantly attenuated 48 h after the influenza vaccination (23.4 ± 6.4 to 20.5 ± 4.9, (p<0.05) but not sham vaccination. Conclusions These findings show that acute inflammation is associated with a temporary deterioration in cardiac autonomic nervous system function in healthy subjects.