title: Inhalation of ultrafine carbon particles alters heart rate and heart rate variability in people with type 2 diabetes.
abstract: BACKGROUND
  Diabetes may confer an increased risk for the cardiovascular health effects of particulate air pollution, but few human clinical studies of air pollution have included people with diabetes. Ultrafine particles (UFP, ≤100 nm in diameter) have been hypothesized to be an important component of particulate air pollution with regard to cardiovascular health effects.
  
  
  METHODS
  17 never-smoker subjects 30-60 years of age, with stable type 2 diabetes but otherwise healthy, inhaled either filtered air (0-10 particles/cm3) or elemental carbon UFP (~107 particles/cm3, ~50 ug/m3, count median diameter 32 nm) by mouthpiece, for 2 hours at rest, in a double-blind, randomized, crossover study design. A digital 12-lead electrocardiogram (ECG) was recorded continuously for 48 hours, beginning 1 hour prior to exposure.
  
  
  RESULTS
  Analysis of 5-minute segments of the ECG during quiet rest showed reduced high-frequency heart rate variability with UFP relative to air exposure (p = 0.014), paralleled by non-significant reductions in time-domain heart rate variability parameters. In the analysis of longer durations of the ECG, we found that UFP exposure increased the heart rate relative to air exposure. During the 21- to 45-hour interval after exposure, the average heart rate increased approximately 8 beats per minute with UFP, compared to 5 beats per minute with air (p = 0.045). There were no UFP effects on cardiac rhythm or repolarization.
  
  
  CONCLUSIONS
  Inhalation of elemental carbon ultrafine particles alters heart rate and heart rate variability in people with type 2 diabetes. Our findings suggest that effects may occur and persist hours after a single 2-hour exposure.
authors.forename: Rathin
authors.initials: R
authors.lastname: Vora
authors.forename: Wojciech
authors.initials: W
authors.lastname: Zareba
authors.forename: Mark J
authors.initials: MJ
authors.lastname: Utell
authors.forename: Anthony P
authors.initials: AP
authors.lastname: Pietropaoli
authors.forename: David
authors.initials: D
authors.lastname: Chalupa
authors.forename: Erika L
authors.initials: EL
authors.lastname: Little
authors.forename: David
authors.initials: D
authors.lastname: Oakes
authors.forename: Jan
authors.initials: J
authors.lastname: Bausch
authors.forename: Jelani
authors.initials: J
authors.lastname: Wiltshire
authors.forename: Mark W
authors.initials: MW
authors.lastname: Frampton
mesh_terms: D000328:Adult; D002244:Carbon / Q000009:adverse effects*; D018592:Cross-Over Studies; D003924:Diabetes Mellitus, Type 2 / Q000175:diagnosis / Q000503:physiopathology*; D004311:Double-Blind Method; D004562:Electrocardiography; D005260:Female; D006321:Heart / Q000187:drug effects* / Q000503:physiopathology; D006339:Heart Rate / Q000187:drug effects*; D006801:Humans; D019570:Inhalation Exposure / Q000009:adverse effects*; D008297:Male; D008875:Middle Aged; D008910:Minnesota; D010316:Particle Size; D052638:Particulate Matter / Q000009:adverse effects*; D018570:Risk Assessment; D013997:Time Factors
chemical_list: D052638:Particulate Matter; D002244:Carbon