[Phase and frequency locking of 0.1 Hz oscillations in heart rhythm and baroreflex control of arterial pressure by respiration with linearly varying frequency in healthy subjects]

We studied the features of functional interaction between the subsystems of autonomic control of heart rate (HR) and arterial pressure (AP) giving rise to 0.1 Hz oscillations in R-R intervals (RRI) and photoplethysmogram (PPG). The study included 25 healthy subjects (6 women and 19 men) aged between 18 and 32 years. The signals of RRI, PPG and respiration were simultaneously recorded under breathing with a frequency linearly increasing from 0.05 Hz to 0.25 Hz within 25 minutes in a sitting position of a subject. The possibility of phase and frequency locking of 0.1 Hz oscillations in RRI and PPG by respiration is shown. We revealed that theses oscillations have different width and location of the intervals of phase and frequency locking by respiration. This distinction points to the functional independence between the mechanisms of autonomic control of 0.1 Hz oscillations in RRI and PPG.