Regression analysis between heart rate variability and baroreflex-related vagus nerve activity in rats.
BACKGROUND
Many previous studies have suggested that the high-frequency (HF) power of the heart rate variability may represent cardiac vagal activity although direct evidence of a correlation between the HF and vagal neuronal activity is still lacking. In the present study, we performed a regression analysis of the HF and vagal neurograms.


RESULTS
Experiments were carried out on adult male Sprague-Dawley rats anesthetized with a continuous infusion of pentobarbital sodium. The baroreflex-related vagus neuronal activities were obtained by nerve or single-fiber recordings. The transient baroreflex response was employed to alter vagus neuronal activities using a bolus injection of phenylephrine (PE). On-line power spectral analysis of the heart rate and a vagal neurogram was performed during the acute baroreflex response. During the test period, systemic arterial pressure immediately increased in response to the PE injection, after which the R-R interval (RR), HF (0.6-2.4 Hz), and vagus nerve and unit activities all dramatically increased. Both nerve and unit activities exhibited good correlations (r > or = 0.7 in all nerve recordings and r > or = 0.6 in 91% of single-fiber recordings) with the HF. There were insignificant differences between the right- and left-side baroreflex-related vagus nerve recordings.


CONCLUSIONS
Our present study provides a direct linkage between the HF and vagus neuronal electrical activity in anesthetized rats.
Kuo
Terry B J
TB
Institute of Neuroscience, Tzu Chi University, Hualien, Taiwan.
Lai
Ching J
CJ
Huang
Yu-Ting
YT
Yang
Cheryl C H
CC
D000818:Animals; D017704:Baroreflex / Q000187:drug effects; D004562:Electrocardiography; D006339:Heart Rate; D008297:Male; D010656:Phenylephrine / Q000494:pharmacology; D051381:Rats; D017207:Rats, Sprague-Dawley; D012044:Regression Analysis; D014630:Vagus Nerve / Q000187:drug effects / Q000502:physiology*
D010656:Phenylephrine