Fig. 5

Typical recordings of a sympathetic nerve stimulation (SNS) command, heart rate (HR), R–R interval (RRI), and arterial pressure (AP) obtained from the metoprolol protocol. The data are displayed as 200-Hz resampled signals. The first random SNS changed HR dynamically with an increase in the mean level of HR. Intravenous (i.v.) administration of metoprolol acutely decreased HR. The second random SNS did not change HR perceivably. RRI showed changes reciprocal to HR. bpm beats/min