Bidirectional augmentation of dynamic heart rate regulation by the autonomic nervous system

Abstract

To characterize dynamic interaction between sympathetic and vagal heart rate control, the authors estimated linear transfer function from stimulation frequency to heart rate in the presence of various patterns of the stimulation of the other nerve. The gain of the transfer function increased by 80.7/spl plusmn/50.5% when 10 Hz tonic vagal stimulation accompanied white noise sympathetic stimulation. The gain was augmented by 24.1/spl plusmn/18.0% when 10 Hz tonic sympathetic stimulation accompanied white noise vagal stimulation. During simultaneous white noise stimulation, the gain was larger than that predicted by individual stimulation. The authors conclude that heart rate regulation is augmented bidirectionally and serves to enhance heart rate regulation under physiological conditions.