Particle toxicity and pollutant gas/particle myocardial infarction

Particle toxicity and pollutant gas/particle
interactions in a rat model of acute
myocardial infarction
John Godleski, MD
Harvard School of Public Health
Rat Model of Acute MI
• Perform left
thoracotomy to
expose heart.
• Cauterize left main
coronary artery to
induce MI.
• Close chest.
Surgical Outcomes
Wellenius et al. , 2004
Sample ECG
QRS
Normal Sinus Rhythm
P
T
Ventricular Premature Beats
VPB
Atrioventricular Block
Block
250 ms
Wellenius et al. , 2002
Experimental Design
Surgery & Recovery
(12-18 hr)
Diazepam
(IP, 12 mg/kg)
Room Air
Exposure to Room Air
(1 hr)
Carbon Black
Exposure to Room Air
(1 hr)
ROFA
Change in VPB Frequency During
Exposures as Compared to Room Air
Exposure
%∆
95% CI
p
ROFA
↑ 566.7%
185.4, 1457.2
<0.0001
Carbon
Black
↓ 52.3
-90.6, 140.5
0.37
Wellenius et al. , 2002
Study Hypotheses
1. Exposure to CAPs will increase arrhythmia
incidence
2. Exposure to low levels of CO will increase
arrhythmia incidence
3. Exposure to a combination of CAPs and CO
will synergistically increase arrhythmia
incidence
Experimental Design
Surgery & Recovery
(12-18 hr)
Diazepam
(IP, 12 mg/kg)
Air Only
Exposure to Filtered Air
(1 hr)
Air+CO
CAPs Only
Exposure to Filtered Air
(1 hr)
CAPs+CO
Harvard Ambient Particle Concentrator
CAPs:
• PM2.5
• Concentration is
~30x ambient
• Composition is
same as ambient
Exposure Characterization
Sampling
Airstream
Sample
Type
Parameter
Mass Concentration
Sulfate
Ambient Air Integrated
Ammonium
Particles
Particle Size Distribution
Continuous Carbon Monoxide
Mass Concentration
Sulfate
Elemental/Organic Carbon
Integrated
Trace Metals
Endotoxins
Concentrated
Air Particles
Non-Volatile Fine Mass
Concentration
Continuous Black Carbon
Particle Number
Concentration
Analytic Method
Gravimetric Analysis
Ion Chromatography
Ion Chromatography
Gravimetric Analysis
Non-Dispersive Infrared
Gravimetric Analysis
Ion Chromatography
Thermal/Optical Reflectance
X-Ray Fluorescence
KLARE Limulus Ameobocyte
Assay
Tapered Element Oscillating
Microbalance
Aethalometer
Condensation Particle Counter
Godleski et al. HEI 2000
Change in VPB Frequency During CAPs and
CO Exposures as Compared to Filtered Air
Exposures
%∆
95% CI
p
CAPs
↑64.2%
-17.7, 227.6
0.16
CO
↓60.4%
-80.7, -18.8
0.012
CAPs/CO*
↓35.0%
-53.6, 246.6
ns
*: In a model assuming no interaction between CAPs and CO
Wellenius et al. , 2004
Effects on Arrhythmia Frequency
400
350
CO Effect
CAPs Effect
250
200
150
100
50
0
-50
ll
Tra
Su nsm
be
pic ural
ar d
ial
Ov
era
Tra
Su nsm
be
pic ural
ar d
ial
ll
-100
Ov
era
% Change
300
Wellenius et al. , 2004
Key Findings
• Animal model for studying arrhythmias is
available
• Frequency ventricular arrhythmias
–
–
–
–
Significantly increased by ROFA
Tendency towards increase by CAPs
Significantly decreased by CO
No interaction was observed between the
effects of CAPs and CO.
Magnitude of Effect by Exposure
Exposure
%∆
95% CI
p
ROFA
↑ 566.7%
185.4, 1457.2
<0.0001
CAPs
↑ 64.2%
-17.7, 227.6
CO
↓ 60.4%
-80.7, -18.8
0.16
0.012
Gurgueira SA, et al. Rapid Increases in the Steady-State
Concentration of Reactive Oxygen Species in the Lungs and
Heart after Particulate Air Pollution Inhalation. Environ. Health
Perspect. 110:749-755 (2002)
Summary
• Particle / Gaseous pollutant effects can be
disentangled in laboratory studies.
• Particles and environmentally relevant levels of
CO have opposite effects on arrhythmias in a
model of acute MI.
• Similar exposure protocols yield similar results in
measurements of in vivo chemiluminescence in the
heart and arrhythmias in the MI studies.
• ROFA has greater toxicity than CAPs.