Spectral analysis of heart rate variability and RVLM neuronal discharge in rats

Spectral analysis was used to study the coherence between the blood pressure (BP) and neuronal discharge (ND), and between the heart rate variability (HRV) and neuronal discharge variability (NDV) in the rostral ventrolateral medulla (RVLM) in rats. The discharges of 28 neurons in the RVLM were recorded. The results revealed that: (1) there is an obvious coherence (k²=0.82±0.18) between ND and BP on spectrum. These neurons were classified as cardiac-related (n=18) if the coherence value was k²⩾0.80; (2) there is also an evident coherence (k²=0.78±0.13) between NDV and high frequency (HF) component of HRV. These neurons might be HRV-related (n=14) if the coherence value was k²⩾0.80. It indicates the integration of cardiac cycle and respiratory rhythm in the RVLM that might be important in cardiorespiratory homeostasis