Contribution of the carotid body chemoreceptors to the modulation of heart rate variability (873.6)

Abstract

We tested the hypothesis that administering low‐dose dopamine (2 mcg/kg/min) to desensitize the carotid body chemoreceptors would alter metrics of heart rate variability (HRV). Electrocardiogram (ECG) recordings were obtained from 18 healthy adults (age = 31 ± 2 years; BMI = 24.6 ± 0.6 kg/m2) during two randomized study days where they received an IV infusion of saline (S) or dopamine (DA). HRV was analyzed during five minute segments at baseline and during infusions of S and DA. Time‐domain analysis of the root mean square of the successive differences (RMSSD) along with spectral domain analysis of low (LF) and high frequency (HF) were obtained. There were no differences (P > 0.05) in respiration rate or blood pressure at any time point. Heart rate increased from baseline during DA (60 ± 2 vs. 63 ± 2 bpm; P < 0.01) and during infusion it was greater in DA vs. S (63 ± 2 vs. 58 ± 2 bpm; P < 0.01). RMSSD decreased from baseline to infusion during DA (68.2 ± 7.6 vs. 51.6 ± 6.0 ms; P < 0.01) and during infusion it was lower in DA vs. S (78.3 ± 10.3 vs. 51.6 ± 6.0 ms; P < 0.01). HF was reduced during DA vs. baseline (1733± 301 vs. 870 ± 171 ms2; P < 0.01), and during infusion DA was also lower than S (1936 ± 471 vs. 870 ± 171 ms2; P = 0.02). There were no changes (P > 0.05) in LF, LF/HF or normalized HF and LF values. These data indicate that during resting conditions the carotid body chemoreceptors likely modulate parasympathetic components of HRV in healthy adults.Grant Funding Source: Supported by NIH R01DK090541 and RO1HL61388