Loading…

Dynamic accentuated antagonism of heart rate control during different levels of vagal nerve stimulation intensity in rats

Accentuated antagonism refers to a phenomenon in which the vagal effect on heart rate (HR) is augmented by background sympathetic tone. The dynamic aspect of accentuated antagonism remains to be elucidated during different levels of vagal nerve stimulation (VNS) intensity. We performed VNS on anesth...

Full description

Saved in:
Bibliographic Details
Published in:American journal of physiology. Regulatory, integrative and comparative physiology integrative and comparative physiology, 2023-02, Vol.324 (2), p.R260-R270
Main Authors: Kawada, Toru, Yokoi, Aimi, Nishiura, Akitsugu, Kakuuchi, Midori, Yokota, Shohei, Matsushita, Hiroki, Li, Meihua, Uemura, Kazunori, Saku, Keita
Format: Article
Language:English
Subjects:
Citations: Items that this one cites
Items that cite this one
Online Access:Get full text
Tags: Add Tag
No Tags, Be the first to tag this record!
Description
Summary:Accentuated antagonism refers to a phenomenon in which the vagal effect on heart rate (HR) is augmented by background sympathetic tone. The dynamic aspect of accentuated antagonism remains to be elucidated during different levels of vagal nerve stimulation (VNS) intensity. We performed VNS on anesthetized rats ( = 8) according to a binary white noise signal with a switching interval of 500 ms at three different stimulation rates (low-intensity: 0-10 Hz, moderate-intensity: 0-20 Hz, and high-intensity: 0-40 Hz). The transfer function from VNS to HR was estimated with and without concomitant tonic sympathetic nerve stimulation (SNS) at 5 Hz. The asymptotic low-frequency (LF) gain (in beats/min/Hz) of the transfer function increased with SNS regardless of the VNS rate [low-intensity: 3.93 ± 0.70 vs. 5.82 ± 0.65 ( = 0.021), moderate-intensity: 3.87 ± 0.62 vs. 5.36 ± 0.53 ( = 0.018), high-intensity: 4.77 ± 0.85 vs. 7.39 ± 1.36 ( = 0.011)]. Moreover, SNS slightly increased the ratio of high-frequency (HF) gain to the LF gain. These effects of SNS were canceled by the pretreatment of ivabradine, an inhibitor of hyperpolarization-activated cyclic nucleotide-gated channels, in another group of rats ( = 6). Although background sympathetic tone antagonizes the vagal effect on mean HR, it enables finer HR control by increasing the dynamic gain of the vagal HR transfer function regardless of VNS intensity. When interpreting the HF component of HR variability, the augmenting effect from background sympathetic tone needs to be considered.
ISSN:0363-6119
1522-1490
DOI:10.1152/ajpregu.00229.2022