Role of efferent sympathoadrenal effects in cooling-induced hemodynamic perturbations in rats: An investigation by spectrum analysis

Yia Ping Liu, Yi Hsien Lin, Chen Cheng Lin, Yu Chieh Lin, Yu Chun Chen, Po Lei Lee, Che Se Tung

Research output: Contribution to journalArticlepeer-review

6 Scopus citations

Abstract

Cold stress may produce hemodynamic perturbations but the underlying mechanisms are still not clear. Spectral analysis was used in this study to explore that sympathoadrenal activation could be involved in mechanisms of hemodynamic perturbations to cooling. Conscious rats after treatment with a control vehicle (saline) compared with withdrawal of sympathetic influences by ganglion blocker hexamethonium (HEX) or chemical sympathectomy guanethidine (GUA) were challenged by stressful cooling as acute immersing all four extremities in ice water (4 ± 2°C) for 10 min. Plasma nitric oxide (NO) and the appearance of Dichroitic notch (DN) were measured in comparison between treatment groups throughout the experimental course. Hemodynamic indices were telemetrically monitored, and variability of blood pressure and heart rate (BPV; HRV) were assessed over a range of frequencies: very-low frequency (VLF: 0.02-0.2 Hz), low frequency (LF: 0.2-0.6 Hz), high frequency (HF: 0.6-3 Hz), normalized (n)LF, nHF, ratio LF/HF of HRV (LF/HF HRV ), and total power (TP: ≦3 Hz). Results showed that the concomitant reciprocal changes of spectral powers existed between frequencies of BPV and HRV to the stressful cooling (i.e. VLF BPV versus VLF HRV , LF BPV versus LFHRV, and nLF BPV versus nLFHRV) which contribute to the underlying mechanisms of sympathetic efferent influences and myogenic cardiovascular responsiveness. Furthermore, compared with the control vehicle in the stressful cooling, HEX restrained the increase of the pressor, tachycardia and VLF BPV , except that VLF HRV was reduced. GUA abolished pressor, however, restrained the increase of the tachycardia, VLF BPV and LF BPV . In addition, GUA reversed the downward tendency of nLF BPV into an upward tendency and attenuated both nLFHRV and LF/HF HRV . DN was virtually undetectable after HEX management but was apparently noticeable after GUA management. Finally, the increase of plasma NO after cooling was diminished after HEX or GUA management. Taken together, these results substantiate that the spectral changes during stressful cooling are highly relevant to the efferent sympathetic rhythmicity and subsequent NO production.

Original languageEnglish
Pages (from-to)312-321
Number of pages10
JournalChinese Journal of Physiology
Volume58
Issue number5
DOIs
StatePublished - 2015

Keywords

  • Guanethidine
  • Hemodynamic perturbations
  • Hexamethonium
  • Spectral powers
  • Stressful cooling
  • Sympathetic influences

Fingerprint

Dive into the research topics of 'Role of efferent sympathoadrenal effects in cooling-induced hemodynamic perturbations in rats: An investigation by spectrum analysis'. Together they form a unique fingerprint.

Cite this