Effects of vagal blockade on the complexity of heart rate variability in rats

Abstract

In this paper we investigate the influence of vagal blockage on heart rate variability complexity measures. Nine conscious rats are injected with methyl-scopolamine brobide (50 μg/kg s.c.). We analyze 10 minute segments of beat-to-beat intervals before and after injection by standard time and frequency domain methods, compression entropy, sample entropy, Poincaré plot, detrended fluctuation analysis and symbolic dynamics. All parameter domains show changes in heart rate variability after vagal blockade, indicating a decrease in heart rate complexity. In conclusion, vagal modulation plays an important role in the generation of heart complexity in rats or, in other words, heart rate complexity measures are sensitive to vagal heart rate modulation.