Heart rate and muscle sympathetic nerve variability during reflex changes of autonomic activity

Low-frequency fluctuations of heart rate are increased by maneuvers, such as standing or hemorrhage, that increase sympathetic outflow to the heart and vasculature

J. P. Saul; R. F. Rea; D. L. Eckberg; R. D. Berger; R. J. Cohen

2017

Scholarcy highlights

  • Low-frequency fluctuations of heart rate are increased by maneuvers, such as standing or hemorrhage, that increase sympathetic outflow to the heart and vasculature
  • To test the hypothesis that low-frequency heart rate fluctuations provide an index of sympathetic efferent activity, we compared power spectral measures of heart rate variability with two measures of sympathetic outflow, peroneal nerve sympathetic activity and antecubital vein plasma norepinephrine concentrations
  • During increases of muscle sympathetic activity and probable reductions of cardiac vagal activity induced by nitroprusside, the fraction of heart rate spectral power at low frequencies, but not the absolute value, correlated significantly with muscle sympathetic activity and plasma norepinephrine
  • During reductions of muscle sympathetic activity and probable elevations of cardiac vagal activity induced by phenylephrine, no measure of heart rate variability correlated significantly with muscle sympathetic activity
  • Division of Health Sciences and Technology, Harvard-MassachusettsInstitute of Technology, Cambridge 02139

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