Spectral analysis of sympathetic discharge, R-R interval and systolic arterial pressure in decerebrate cats

Nicola Montano, Federico Lombardi, Tomaso Gnecchi Ruscone, Mauro Contini, Maria Luisa Finocchiaro, Giuseppe Baselli, Alberto Porta, Sergio Cerutti, Alberto Malliani

Research output: Contribution to journalArticlepeer-review


In 19 decerebrate and artificially ventilated cats, we analyzed, with a power spectral methodology, the variability simultaneously present in R-R interval and in thoracic preganglionic sympathetic outflow. R-R interval was characterized, as already described in humans and other experimental preparations, by two rhythmic components occurring at a frequency of about 0.1 Hz (low-frequency, LF) and at one corresponding to respiratory rate (high-frequency, HF) which, in these experiments, was set at 0.32 Hz. Two similar rhythmic components were also present in the sympathetic discharge. Arterial pressure changes were produced by aorta or vena cava flow obstruction in order to produce reflex responses in sympathetic activity. Reflex sympathetic excitations induced an increase in the LF component of both R-R interval and sympathetic discharge variabilities, while the HF components were simultaneously reduced. In contrast, reflex sympathetic inhibitions were accompanied by a decrease in LF components of both variability signals, while the HF components were simultaneously increased. A significant and positive correlation was found between changes in impulse activity and the amplitude of LF component of either R-R interval or sympathetic discharge variabilities. These data support the hypothesis that the low-frequency component of R-R variability can be used as a marker of sympathetic modulation.

Original languageEnglish
Pages (from-to)21-31
Number of pages11
JournalJournal of the Autonomic Nervous System
Issue number1
Publication statusPublished - 1992


  • Efferent sympathetic discharge
  • Heart rate variability
  • Power spectrum analysis
  • Sympatho-vagal interaction

ASJC Scopus subject areas

  • Physiology
  • Clinical Neurology
  • Neuroscience(all)


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