Changes in Heart Period, Heart Period Variability, and a Spectral Analysis Estimate of Respiratory Sinus Arrhythmias During Aortic Nerve Stimulation in Rabbits

Abstract

Changes in heart period, heart period variance (HPV), and the respiratory component of HPV were examined during enhanced negative chronotropic influences on the heart produced by aortic depressor nerve (ADN) stimulation in urethane anesthetized rabbits. Spectral analysis was used to quantify the respiratory component of HPV, respiratory sinus arrhythmia (RSA). The statistic derived from spectral analysis which describes RSA, V̂, has been proposed to be sensitive to vagal influences on the heart. Stimulation of the ADN significantly increased V̂, heart period, and HPV. However, unlike V̂ and heart period, HPV values remained elevated following the end of stimulation. Propranolol administration did not alter the magnitude of the evoked increase in V̂, heart period, or HPV. In contrast, administration of atropine abolished the increases due to stimulation in all three measures. Heart period exhibited a monotonic relationship with stimulation current intensity. This relationship disappeared after propranolol administration suggesting sympathetic mediation. The results suggest that V̂ is sensitive to manipulations of vagal influences on the heart. In addition, V̂ often responds in a different manner from heart period and HPV.

The potent role of increased sympathetic tone in pathogenesis of essential hypertension with neurovascular compression

“…16,22,23 Thus the low-frequency component is believed to be an index of sympathetic activity. The high-frequency component is thought to be a quantitative index of parasympathetic activity, 16,22,23 because it reflects respiratory sinus arrhythmia, which is modulated by cardiac vagal tone, 24,25 decreases when a person is standing, and is blocked by intravenously administered atropine. 16,22,23 Patients with essential hypertension with neurovascular compression showed relatively high values of low-frequency PSD compared with the other groups in the present study (Figure 2).…”

Effects of paced respiration on heart period and heart period variability

“…The high frequency component~HF!, with a center frequency in the range of the respiration rate, reflects the respiratory sinus arrhythmia~RSA!. The RSA is mainly transmitted by the parasympathetic branch of the autonomic nervous system~Akselrod Cacioppo et al, 1994;Chess, Tam, & Calaresu, 1975;Katona & Jih, 1975;McCabe, Yongue, Porges, & Ackles, 1984;Pomeranz et al, 1985!. The low frequency component~LF!, with a frequency around 0.1 Hz, is related to the Mayer-Traube-Hering blood pressure waves. It is still not clear to what extent sympathetic and parasympathetic influences contribute to this component.…”

Vagal tone during quiet sleep in normal human term fetuses

“…This has been accomplished in neonates by performing a spectral analysis of the beat-tobeat fluctuations in heart period after detrending the data to meet the assumption of stationarity. As demonstrated in a series of animal studies (McCabe, Yongue, Ackles, & Porges, 1985;McCabe, Yongue, Porges, & Ackles, 1984;Yongue et al, 1982), the area under the power spectrum curve corresponding to the frequency of respiration provides a measure of parasympathetic activity, which Porges (1985) has called vagal tone (V).…”