title: Effects of on-road highway aerosol exposures on autonomic responses in aged, spontaneously hypertensive rats.
abstract: Epidemiological studies associate ambient particulate pollution with adverse health outcomes in elderly individuals with cardiopulmonary diseases. We hypothesized that freshly generated ultrafine particles (UFP) contribute to these effects, as they are present in high number concentrations on highways and vehicle passengers are exposed directly to them. Aged spontaneously hypertensive rats (9-12 mo) with implanted radiotelemetry devices were exposed to highway aerosol or filtered, gas-denuded (clean) air using an on-road exposure system to examine effects on heart rate (HR) and heart-rate variability (HRV). On the day of exposure, rats were pretreated with low-dose inhaled or injected lipopolysaccharide (LPS) to simulate respiratory tract or systemic inflammation, respectively. Exposures (6 h) in compartmentalized whole-body chambers were performed in an air conditioned compartment of a mobile laboratory on I-90 between Rochester and Buffalo, NY. HRV parameters were calculated from telemetric blood pressure signals and analyzed for the baseline period and for the first 32 h postexposure. The aerosol size (count median diameter = 15-20 nm; geometric standard deviation = 1.4-4.3) and number concentration (1.95-5.62 x 105/cm3) indicated the predominance of UFP. Intraperitoneal LPS significantly affected all of the parameters in a time-dependent manner; response patterns after inhaled or injected LPS pretreatment were similar, but more prolonged and greater in LPS-injected rats. A significant effect of highway aerosol was found, irrespective of pretreatment, which resulted in decreased HR in comparison to clean air-exposed rats. This effect was more persistent ( approximately 14 h) in those rats that received ip LPS as compared to saline. The highway aerosol also significantly affected short-term alterations in autonomic control of HR, as evidenced by elevations in normalized high frequency power and decreased vagosympathetic balance. These findings show that environmental exposure concentrations of mixed traffic-related UFP/gas-phase emissions can affect the autonomic nervous system.
authors.affiliation: Department of Environmental Medicine, University of Rochester, Rochester, New York, USA.
authors.forename: Alison
authors.initials: A
authors.lastname: Elder
authors.forename: Jean-Philippe
authors.initials: JP
authors.lastname: Couderc
authors.forename: Robert
authors.initials: R
authors.lastname: Gelein
authors.forename: Shirley
authors.initials: S
authors.lastname: Eberly
authors.forename: Christopher
authors.initials: C
authors.lastname: Cox
authors.forename: Xiaojuang
authors.initials: X
authors.lastname: Xia
authors.forename: Wojciech
authors.initials: W
authors.lastname: Zareba
authors.forename: Philip
authors.initials: P
authors.lastname: Hopke
authors.forename: Winthrop
authors.initials: W
authors.lastname: Watts
authors.forename: David
authors.initials: D
authors.lastname: Kittelson
authors.forename: Mark
authors.initials: M
authors.lastname: Frampton
authors.forename: Mark
authors.initials: M
authors.lastname: Utell
authors.forename: Günter
authors.initials: G
authors.lastname: Oberdörster
mesh_terms: D000280:Administration, Inhalation; D000336:Aerosols; D000367:Age Factors; D000375:Aging; D000393:Air Pollutants / Q000633:toxicity*; D000818:Animals; D001334:Automobile Driving; D001341:Autonomic Nervous System / Q000187:drug effects*; D001794:Blood Pressure / Q000187:drug effects*; D004562:Electrocardiography; D006339:Heart Rate / Q000187:drug effects; D006973:Hypertension / Q000503:physiopathology*; D007249:Inflammation / Q000139:chemically induced / Q000503:physiopathology; D019570:Inhalation Exposure; D007274:Injections, Intraperitoneal; D008070:Lipopolysaccharides / Q000008:administration & dosage; D008297:Male; D010316:Particle Size; D051381:Rats; D011918:Rats, Inbred SHR; D013686:Telemetry; D013997:Time Factors; D001335:Vehicle Emissions / Q000633:toxicity*
chemical_list: D000336:Aerosols; D000393:Air Pollutants; D008070:Lipopolysaccharides; D001335:Vehicle Emissions