title: The influence of inhaled multi-walled carbon nanotubes on the autonomic nervous system.
abstract: BACKGROUND
  Heart rate and cardiovascular function are regulated by the autonomic nervous system. Heart rate variability (HRV) as a marker reflects the activity of autonomic nervous system. The prognostic significance of HRV in cardiovascular disease has been reported in clinical and epidemiological studies. The present study focused on the influence of inhaled multi-walled carbon nanotubes (MWCNTs) on autonomic nervous system by HRV analysis.
  
  
  METHODS
  Male Sprague-Dawley rats were pre-implanted with a telemetry device and kept in the individual cages for recovery. At week four after device implantation, rats were exposed to MWCNTs for 5 h at a concentration of 5 mg/m(3). The real-time EKGs were recorded by a telemetry system at pre-exposure, during exposure, 1 day and 7 days post-exposure. HRV was measured by root mean square of successive differences (RMSSD); the standard deviation of inter-beat (RR) interval (SDNN); the percentage of successive RR interval differences greater than 5 ms (pNN5) and 10 ms (pNN10); low frequency (LF) and high frequency (HF).
  
  
  RESULTS
  Exposure to MWCNTs increased the percentage of differences between adjacent R-R intervals over 10 ms (pNN10) (p < 0.01), RMSSD (p < 0.01), LF (p < 0.05) and HF (p < 0.01).
  
  
  CONCLUSIONS
  Inhalation of MWCNTs significantly alters the balance between sympathetic and parasympathetic nervous system. Whether such transient alterations in autonomic nervous performance would alter cardiovascular function and raise the risk of cardiovascular events in people with pre-existing cardiovascular conditions warrants further study.
authors: Health Effects Laboratory Division, Pathology and Physiology Research Branch, National Institute for Occupational Safety and Health, 1095 Willowdale Road, Morgantown, WV, 26505, USA. wnr3@cdc.gov.
authors: W
authors: W
authors: Zheng
authors: Health Effects Laboratory Division, Pathology and Physiology Research Branch, National Institute for Occupational Safety and Health, 1095 Willowdale Road, Morgantown, WV, 26505, USA. wdm9@cdc.gov.
authors: W
authors: W
authors: McKinney
authors: Health Effects Laboratory Division, Pathology and Physiology Research Branch, National Institute for Occupational Safety and Health, 1095 Willowdale Road, Morgantown, WV, 26505, USA. mqk1@cdc.gov.
authors: M
authors: M
authors: Kashon
authors: Health Effects Laboratory Division, Pathology and Physiology Research Branch, National Institute for Occupational Safety and Health, 1095 Willowdale Road, Morgantown, WV, 26505, USA. zvj4@cdc.gov.
authors: R
authors: R
authors: Salmen
authors: Department of Pharmaceutical Sciences, West Virginia University, Morgantown, WV, 26505, USA. vcastran@hsc.wvu.edu.
authors: V
authors: V
authors: Castranova
authors: Health Effects Laboratory Division, Pathology and Physiology Research Branch, National Institute for Occupational Safety and Health, 1095 Willowdale Road, Morgantown, WV, 26505, USA. hvn4@cdc.gov.|Department of Physiology and Pharmacology, West Virginia University, Morgantown, WV, 26505, USA. hvn4@cdc.gov.
authors: H
authors: H
authors: Kan
mesh_terms: D000280:Administration, Inhalation; D000818:Animals; D001145:Arrhythmias, Cardiac / Q000139:chemically induced* / Q000503:physiopathology; D001341:Autonomic Nervous System / Q000187:drug effects* / Q000503:physiopathology; D002319:Cardiovascular System / Q000187:drug effects* / Q000294:innervation; D015716:Electrocardiography, Ambulatory; D006339:Heart Rate / Q000187:drug effects*; D008297:Male; D037742:Nanotubes, Carbon / Q000633:toxicity*; D017207:Rats, Sprague-Dawley; D018570:Risk Assessment; D013686:Telemetry; D013997:Time Factors
chemical_list: D037742:Nanotubes, Carbon