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Perez CM, Hazari MS, Ledbetter AD, Haykal-Coates N, Carll AP, Cascio WE, Winsett DW, Costa DL, Farraj AK. Acrolein inhalation alters arterial blood gases and triggers carotid body-mediated cardiovascular responses in hypertensive rats. Inhal Toxicol 2015; 27:54-63. [PMID: 25600140 DOI: 10.3109/08958378.2014.984881] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023]
Abstract
CONTEXT Air pollution exposure affects autonomic function, heart rate, blood pressure and left ventricular function. While the mechanism for these effects is uncertain, several studies have reported that air pollution exposure modifies activity of the carotid body, the major organ that senses changes in arterial oxygen and carbon dioxide levels, and elicits downstream changes in autonomic control and cardiac function. OBJECTIVE We hypothesized that exposure to acrolein, an unsaturated aldehyde and mucosal irritant found in cigarette smoke and diesel exhaust, would activate the carotid body chemoreceptor response and lead to secondary cardiovascular responses in rats. MATERIALS AND METHODS Spontaneously hypertensive (SH) rats were exposed once for 3 h to 3 ppm acrolein gas or filtered air in whole body plethysmograph chambers. To determine if the carotid body mediated acrolein-induced cardiovascular responses, rats were pretreated with an inhibitor of cystathionine γ-lyase (CSE), an enzyme essential for carotid body signal transduction. RESULTS Acrolein exposure induced several cardiovascular effects. Systolic, diastolic and mean arterial blood pressure increased during exposure, while cardiac contractility decreased 1 day after exposure. The cardiovascular effects were associated with decreases in pO2, breathing frequency and expiratory time, and increases in sympathetic tone during exposure followed by parasympathetic dominance after exposure. The CSE inhibitor prevented the cardiovascular effects of acrolein exposure. DISCUSSION AND CONCLUSION Pretreatment with the CSE inhibitor prevented the cardiovascular effects of acrolein, suggesting that the cardiovascular responses with acrolein may be mediated by carotid body-triggered changes in autonomic tone. (This abstract does not reflect EPA policy.).
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Affiliation(s)
- Christina M Perez
- Curriculum in Toxicology, University of North Carolina , Chapel Hill, NC , USA
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Carll AP, Haykal-Coates N, Winsett DW, Hazari MS, Ledbetter AD, Richards JH, Cascio WE, Costa DL, Farraj AK. Cardiomyopathy confers susceptibility to particulate matter-induced oxidative stress, vagal dominance, arrhythmia and pulmonary inflammation in heart failure-prone rats. Inhal Toxicol 2015; 27:100-12. [PMID: 25600220 DOI: 10.3109/08958378.2014.995387] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
Acute exposure to ambient fine particulate matter (PM2.5) is tied to cardiovascular morbidity and mortality, especially among those with prior cardiac injury. The mechanisms and pathophysiological events precipitating these outcomes remain poorly understood but may involve inflammation, oxidative stress, arrhythmia and autonomic nervous system imbalance. Cardiomyopathy results from cardiac injury, is the leading cause of heart failure, and can be induced in heart failure-prone rats through sub-chronic infusion of isoproterenol (ISO). To test whether cardiomyopathy confers susceptibility to inhaled PM2.5 and can elucidate potential mechanisms, we investigated the cardiophysiologic, ventilatory, inflammatory and oxidative effects of a single nose-only inhalation of a metal-rich PM2.5 (580 µg/m(3), 4 h) in ISO-pretreated (35 days × 1.0 mg/kg/day sc) rats. During the 5 days post-treatment, ISO-treated rats had decreased HR and BP and increased pre-ejection period (PEP, an inverse correlate of contractility) relative to saline-treated rats. Before inhalation exposure, ISO-pretreated rats had increased PR and ventricular repolarization time (QT) and heterogeneity (Tp-Te). Relative to clean air, PM2.5 further prolonged PR-interval and decreased systolic BP during inhalation exposure; increased tidal volume, expiratory time, heart rate variability (HRV) parameters of parasympathetic tone and atrioventricular block arrhythmias over the hours post-exposure; increased pulmonary neutrophils, macrophages and total antioxidant status one day post-exposure; and decreased pulmonary glutathione peroxidase 8 weeks after exposure, with all effects occurring exclusively in ISO-pretreated rats but not saline-pretreated rats. Ultimately, our findings indicate that cardiomyopathy confers susceptibility to the oxidative, inflammatory, ventilatory, autonomic and arrhythmogenic effects of acute PM2.5 inhalation.
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Affiliation(s)
- Alex P Carll
- Environmental Sciences and Engineering, University of North Carolina , Chapel Hill, NC , USA
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Hazari MS, Haykal-Coates N, Winsett DW, King C, Krantz QT, Gilmour MI, Farraj AK. The effects of B0, B20, and B100 soy biodiesel exhaust on aconitine-induced cardiac arrhythmia in spontaneously hypertensive rats. Inhal Toxicol 2015; 27:557-63. [PMID: 26514783 DOI: 10.3109/08958378.2015.1054967] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2015] [Revised: 05/19/2015] [Accepted: 05/20/2015] [Indexed: 11/13/2022]
Abstract
CONTEXT Diesel exhaust (DE) has been shown to increase the risk of cardiac arrhythmias. Although biodiesel has been proposed as a "safer" alternative to diesel, it is still uncertain whether it actually poses less threat. OBJECTIVE We hypothesized that exposure to pure or 20% soy biodiesel exhaust (BDE) would cause less sensitivity to aconitine-induced arrhythmia than DE in rats. METHODS Spontaneously hypertensive (SH) rats implanted with radiotelemeters were exposed once or for 5 d (4 h) to either 50 mg/m(3) (low), 150 mg/m(3) (medium), or 500 mg/m(3) (high) of DE (B0), 20% (B20) or 100% (B100) soy biodiesel exhaust. Arrhythmogenesis was assessed 24 h later by continuous infusion of aconitine, an arrhythmogenic drug, while heart rate (HR), and electrocardiogram (ECG) were monitored. RESULTS Rats exposed once or for 5 d to low, medium, or high B0 developed arrhythmia at significantly lower doses of aconitine than controls, whereas rats exposed to B20 were only consistently sensitive after 5 d of the high concentration. B100 caused mild arrhythmia sensitivity at the low concentration, only after 5 d of exposure at the medium concentration and after either a single or 5 d at the high concentration. DISCUSSION AND CONCLUSIONS These data demonstrate that exposure to B20 causes less sensitivity to arrhythmia than B0 and B100. This diminished effect may be due to lower irritant components such as acrolein and nitrogen oxides. Thus, in terms of cardiac health, B20 may be a safer option than both of the pure forms.
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Affiliation(s)
- Mehdi S Hazari
- a Environmental Public Health Division, NHEERL, U.S. Environmental Protection Agency, Research Triangle Park , NC , USA
| | - Najwa Haykal-Coates
- a Environmental Public Health Division, NHEERL, U.S. Environmental Protection Agency, Research Triangle Park , NC , USA
| | - Darrell W Winsett
- a Environmental Public Health Division, NHEERL, U.S. Environmental Protection Agency, Research Triangle Park , NC , USA
| | - Charly King
- a Environmental Public Health Division, NHEERL, U.S. Environmental Protection Agency, Research Triangle Park , NC , USA
| | - Q Todd Krantz
- a Environmental Public Health Division, NHEERL, U.S. Environmental Protection Agency, Research Triangle Park , NC , USA
| | - M Ian Gilmour
- a Environmental Public Health Division, NHEERL, U.S. Environmental Protection Agency, Research Triangle Park , NC , USA
| | - Aimen K Farraj
- a Environmental Public Health Division, NHEERL, U.S. Environmental Protection Agency, Research Triangle Park , NC , USA
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Farraj AK, Haykal-Coates N, Winsett DW, Gilmour MI, King C, Krantz QT, Richards J, Hazari MS. Comparative electrocardiographic, autonomic and systemic inflammatory responses to soy biodiesel and petroleum diesel emissions in rats. Inhal Toxicol 2015; 27:564-75. [PMID: 26514784 DOI: 10.3109/08958378.2015.1057884] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2015] [Revised: 05/08/2015] [Accepted: 05/30/2015] [Indexed: 01/23/2023]
Abstract
CONTEXT Biodiesel fuel represents an alternative to high particulate matter (PM)-emitting petroleum-based diesel fuels, yet uncertainty remains regarding potential biodiesel combustion emission health impacts. OBJECTIVE The purpose of this study was to compare cardiovascular responses to pure and blended biodiesel fuel emissions relative to petroleum diesel exhaust (DE). MATERIALS AND METHODS Spontaneously hypertensive rats were exposed for 4 h per day for four days via whole body inhalation to combustion emissions (based on PM concentrations 50, 150 or 500 μg/m(3) or filtered air) from pure (B100) or blended (B20) soy biodiesel, or to pure petroleum DE (B0). Electrocardiogram (ECG) and heart rate variability (HRV, an index of autonomic balance) were monitored before, during and after exposure while pulmonary and systemic inflammation were assessed one day after the final exposure. ECG and HRV data and inflammatory data were statistically analyzed using a linear mixed model for repeated measures and an analysis of variance, respectively. RESULTS B100 and B0, but not B20, increased HRV during all exposure days at the highest concentration indicating increased parasympathetic tone. Electrocardiographic data were mixed. B100 and B0, but not B20, caused significant changes in one or more of the following: serum C-reactive protein, total protein, low density lipoprotein (LDL) and high density lipoprotein (HDL) cholesterol, and blood urea nitrogen (BUN) and plasma angiotensin converting enzyme (ACE) and fibrinogen. DISCUSSION AND CONCLUSIONS Although responses to emissions from all fuels were mixed and relatively mild, some findings point to a reduced cardiovascular impact of blended biodiesel fuel emissions.
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Affiliation(s)
- A K Farraj
- a Environmental Public Health Division, NHEERL, US Environmental Protection Agency , Research Triangle Park , NC , USA
| | - N Haykal-Coates
- a Environmental Public Health Division, NHEERL, US Environmental Protection Agency , Research Triangle Park , NC , USA
| | - D W Winsett
- a Environmental Public Health Division, NHEERL, US Environmental Protection Agency , Research Triangle Park , NC , USA
| | - M I Gilmour
- a Environmental Public Health Division, NHEERL, US Environmental Protection Agency , Research Triangle Park , NC , USA
| | - C King
- a Environmental Public Health Division, NHEERL, US Environmental Protection Agency , Research Triangle Park , NC , USA
| | - Q T Krantz
- a Environmental Public Health Division, NHEERL, US Environmental Protection Agency , Research Triangle Park , NC , USA
| | - J Richards
- a Environmental Public Health Division, NHEERL, US Environmental Protection Agency , Research Triangle Park , NC , USA
| | - M S Hazari
- a Environmental Public Health Division, NHEERL, US Environmental Protection Agency , Research Triangle Park , NC , USA
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Perez CM, Ledbetter AD, Hazari MS, Haykal-Coates N, Carll AP, Winsett DW, Costa DL, Farraj AK. Hypoxia stress test reveals exaggerated cardiovascular effects in hypertensive rats after exposure to the air pollutant acrolein. Toxicol Sci 2013; 132:467-77. [PMID: 23335627 DOI: 10.1093/toxsci/kft008] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022] Open
Abstract
Exposure to air pollution increases the risk of cardiovascular morbidity and mortality, especially in susceptible populations. Despite increased risk, adverse responses are often delayed and require additional stress tests to reveal latent effects of exposure. The goal of this study was to use an episode of "transient hypoxia" as an extrinsic stressor to uncover latent susceptibility to environmental pollutants in a rodent model of hypertension. We hypothesized that exposure to acrolein, an unsaturated aldehyde and mucosal irritant found in cigarette smoke, diesel exhaust, and power plant emissions, would increase cardiopulmonary sensitivity to hypoxia, particularly in hypertensive rats. Spontaneously hypertensive and Wistar Kyoto (normotensive) rats, implanted with radiotelemeters, were exposed once for 3h to 3 ppm acrolein gas or filtered air in whole-body plethysmograph chambers and challenged with a 10% oxygen atmosphere (10min) 24h later. Acrolein exposure increased heart rate, blood pressure, breathing frequency, and minute volume in hypertensive rats and also increased the heart rate variability parameter LF, suggesting a potential role for increased sympathetic tone. Normotensive rats only had increased blood pressure during acrolein exposure. The hypoxia stress test after acrolein exposure revealed increased diastolic blood pressure only in hypertensive rats and increased minute volume and expiratory time only in normotensive rats. These results suggest that hypertension confers exaggerated sensitivity to air pollution and that the hypoxia stress test is a novel tool to reveal the potential latent effects of air pollution exposure.
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Affiliation(s)
- Christina M Perez
- Curriculum in Toxicology, University of North Carolina, Chapel Hill, North Carolina 27514, USA
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Carll AP, Lust RM, Hazari MS, Perez CM, Krantz QT, King CJ, Winsett DW, Cascio WE, Costa DL, Farraj AK. Diesel exhaust inhalation increases cardiac output, bradyarrhythmias, and parasympathetic tone in aged heart failure-prone rats. Toxicol Sci 2012; 131:583-95. [PMID: 23047911 DOI: 10.1093/toxsci/kfs295] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Acute air pollutant inhalation is linked to adverse cardiac events and death, and hospitalizations for heart failure. Diesel engine exhaust (DE) is a major air pollutant suspected to exacerbate preexisting cardiac conditions, in part, through autonomic and electrophysiologic disturbance of normal cardiac function. To explore this putative mechanism, we examined cardiophysiologic responses to DE inhalation in a model of aged heart failure-prone rats without signs or symptoms of overt heart failure. We hypothesized that acute DE exposure would alter heart rhythm, cardiac electrophysiology, and ventricular performance and dimensions consistent with autonomic imbalance while increasing biochemical markers of toxicity. Spontaneously hypertensive heart failure rats (16 months) were exposed once to whole DE (4h, target PM(2.5) concentration: 500 µg/m(3)) or filtered air. DE increased multiple heart rate variability (HRV) parameters during exposure. In the 4h after exposure, DE increased cardiac output, left ventricular volume (end diastolic and systolic), stroke volume, HRV, and atrioventricular block arrhythmias while increasing electrocardiographic measures of ventricular repolarization (i.e., ST and T amplitudes, ST area, T-peak to T-end duration). DE did not affect heart rate relative to air. Changes in HRV positively correlated with postexposure changes in bradyarrhythmia frequency, repolarization, and echocardiographic parameters. At 24h postexposure, DE-exposed rats had increased serum C-reactive protein and pulmonary eosinophils. This study demonstrates that cardiac effects of DE inhalation are likely to occur through changes in autonomic balance associated with modulation of cardiac electrophysiology and mechanical function and may offer insights into the adverse health effects of traffic-related air pollutants.
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Affiliation(s)
- Alex P Carll
- Environmental Sciences and Engineering, University of North Carolina, Chapel Hill, North Carolina 27599, USA
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Hazari MS, Callaway J, Winsett DW, Lamb C, Haykal-Coates N, Krantz QT, King C, Costa DL, Farraj AK. Dobutamine "stress" test and latent cardiac susceptibility to inhaled diesel exhaust in normal and hypertensive rats. Environ Health Perspect 2012; 120:1088-93. [PMID: 22543081 PMCID: PMC3440084 DOI: 10.1289/ehp.1104684] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/01/2011] [Accepted: 04/27/2012] [Indexed: 05/25/2023]
Abstract
BACKGROUND Exercise "stress" testing is a screening tool used to determine the amount of stress for which the heart can compensate before developing abnormal rhythm or ischemia, particularly in susceptible persons. Although this approach has been used to assess risk in humans exposed to air pollution, it has never been applied to rodent studies. OBJECTIVE We hypothesized that a single exposure to diesel exhaust (DE) would increase the risk of adverse cardiac events such as arrhythmia and myocardial ischemia in rats undergoing a dobutamine challenge test, which can be used to mimic exercise-like stress. METHODS Wistar-Kyoto normotensive (WKY) and spontaneously hypertensive (SH) rats implanted with radiotelemeters and a chronic intravenous catheter were whole-body exposed to 150 μg/m3 DE for 4 hr. Increasing doses of dobutamine, a β1-adrenergic agonist, were administered to conscious unrestrained rats 24 hr later to elicit the cardiac response observed during exercise while heart rate (HR) and electrocardiogram (ECG) were monitored. RESULTS A single exposure to DE potentiated the HR response of WKY and SH rats during dobutamine challenge and prevented HR recovery at rest. During peak challenge, DE-exposed SH rats had lower overall HR variability when compared with controls, in addition to transient ST depression. All DE-exposed animals also had increased arrhythmias. CONCLUSIONS These results are the first evidence that rats exhibit stress-induced cardiac dysrhythmia and ischemia sensitivity comparable to humans after a single exposure to a toxic air pollutant, particularly when in the presence of underlying cardiovascular disease. Thus, exposure to low concentrations of air pollution can impair the heart's ability to respond to stress and increase the risk of subsequent triggered dysfunction.
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Affiliation(s)
- Mehdi S Hazari
- Environmental Public Health Division, National Health and Environmental Effects Research Laboratory, U.S. Environmental Protection Agency, Research Triangle Park, North Carolina 27711, USA.
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Carll AP, Hazari MS, Perez CM, Krantz QT, King CJ, Winsett DW, Costa DL, Farraj AK. Whole and particle-free diesel exhausts differentially affect cardiac electrophysiology, blood pressure, and autonomic balance in heart failure-prone rats. Toxicol Sci 2012; 128:490-9. [PMID: 22543275 DOI: 10.1093/toxsci/kfs162] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023] Open
Abstract
Epidemiological studies strongly link short-term exposures to vehicular traffic and particulate matter (PM) air pollution with adverse cardiovascular (CV) events, especially in those with preexisting CV disease. Diesel engine exhaust is a key contributor to urban ambient PM and gaseous pollutants. To determine the role of gaseous and particulate components in diesel exhaust (DE) cardiotoxicity, we examined the effects of a 4-h inhalation of whole DE (wDE) (target PM concentration: 500 µg/m(3)) or particle-free filtered DE (fDE) on CV physiology and a range of markers of cardiopulmonary injury in hypertensive heart failure-prone rats. Arterial blood pressure (BP), electrocardiography, and heart rate variability (HRV), an index of autonomic balance, were monitored. Both fDE and wDE decreased BP and prolonged PR interval during exposure, with more effects from fDE, which additionally increased HRV triangular index and decreased T-wave amplitude. fDE increased QTc interval immediately after exposure, increased atrioventricular (AV) block Mobitz II arrhythmias shortly thereafter, and increased serum high-density lipoprotein 1 day later. wDE increased BP and decreased HRV root mean square of successive differences immediately postexposure. fDE and wDE decreased heart rate during the 4th hour of postexposure. Thus, DE gases slowed AV conduction and ventricular repolarization, decreased BP, increased HRV, and subsequently provoked arrhythmias, collectively suggesting parasympathetic activation; conversely, brief BP and HRV changes after exposure to particle-containing DE indicated a transient sympathetic excitation. Our findings suggest that whole- and particle-free DE differentially alter CV and autonomic physiology and may potentially increase risk through divergent pathways.
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Affiliation(s)
- Alex P Carll
- U.S. Environmental Protection Agency, Environmental Public Health Division, PO B143-01, Research Triangle Park, NC 27711, USA
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Farraj AK, Hazari MS, Winsett DW, Kulukulualani A, Carll AP, Haykal-Coates N, Lamb CM, Lappi E, Terrell D, Cascio WE, Costa DL. Overt and latent cardiac effects of ozone inhalation in rats: evidence for autonomic modulation and increased myocardial vulnerability. Environ Health Perspect 2012; 120:348-54. [PMID: 22138703 PMCID: PMC3295357 DOI: 10.1289/ehp.1104244] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/21/2011] [Accepted: 12/02/2011] [Indexed: 05/22/2023]
Abstract
BACKGROUND Ozone (O₃) is a well-documented respiratory oxidant, but increasing epidemiological evidence points to extrapulmonary effects, including positive associations between ambient O₃ concentrations and cardiovascular morbidity and mortality. OBJECTIVE With preliminary reports linking O₃ exposure with changes in heart rate (HR), we investigated the hypothesis that a single inhalation exposure to O₃ will cause concentration-dependent autonomic modulation of cardiac function in rats. METHODS Rats implanted with telemeters to monitor HR and cardiac electrophysiology [electrocardiography (ECG)] were exposed once by whole-body inhalation for 4 hr to 0.2 or 0.8 ppm O₃ or filtered air. A separate cohort was tested for vulnerability to aconitine-induced arrhythmia 24 hr after exposure. RESULTS Exposure to 0.8 ppm O₃ caused bradycardia, PR prolongation, ST depression, and substantial increases in atrial premature beats, sinoatrial block, and atrioventricular block, accompanied by concurrent increases in several HR variability parameters that were suggestive of increased parasympathetic tone. Low-O₃ exposure failed to elicit any overt changes in autonomic tone, heart rhythm, or ECG. However, both 0.2 and 0.8 ppm O₃ increased sensitivity to aconitine-induced arrhythmia formation, suggesting a latent O₃-induced alteration in myocardial excitability. CONCLUSIONS O₃ exposure causes several alterations in cardiac electrophysiology that are likely mediated by modulation of autonomic input to the heart. Moreover, exposure to low O₃ concentrations may cause subclinical effects that manifest only when triggered by a stressor, suggesting that the adverse health effects of ambient levels of air pollutants may be insidious and potentially underestimated.
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Affiliation(s)
- Aimen K Farraj
- Environmental Public Health Division, National Health and Environmental Effects Research Laboratory, U.S. Environmental Protection Agency, Research Triangle Park, North Carolina 27711, USA.
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Lamb CM, Hazari MS, Haykal-Coates N, Carll AP, Krantz QT, King C, Winsett DW, Cascio WE, Costa DL, Farraj AK. Divergent electrocardiographic responses to whole and particle-free diesel exhaust inhalation in spontaneously hypertensive rats. Toxicol Sci 2011; 125:558-68. [PMID: 22052608 DOI: 10.1093/toxsci/kfr296] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Diesel exhaust (DE) is a major contributor to traffic-related fine particulate matter (PM)(2.5). Although inroads have been made in understanding the mechanisms of PM-related health effects, DE's complex mixture of PM, gases, and volatile organics makes it difficult to determine how the constituents contribute to DE's effects. We hypothesized that exposure to particle-filtered DE (fDE; gases alone) will elicit less cardiac effects than whole DE (wDE; particles plus gases). In addition, we hypothesized that spontaneously hypertensive (SH) rats will be more sensitive to the electrocardiographic effects of DE exposure than Wistar Kyoto rats (WKY; background strain with normal blood pressure). SH and WKY rats, implanted with telemeters to monitor electrocardiogram and heart rate (HR), were exposed once for 4 h to 150 μg/m(3) or 500 μg/m(3) of wDE (gases plus PM) or fDE (gases alone) DE, or filtered air. Exposure to fDE, but not wDE, caused immediate electrocardiographic alterations in cardiac repolarization (ST depression) and atrioventricular conduction block (PR prolongation) as well as bradycardia in SH rats. Exposure to wDE, but not fDE, caused postexposure ST depression and increased sensitivity to the pulmonary C fiber agonist capsaicin in SH rats. The only notable effect of DE exposure in WKY rats was a decrease in HR. Taken together, hypertension may predispose to the potential cardiac effects of DE and components of DE may have divergent effects with some eliciting immediate irritant effects (e.g., gases), whereas others (e.g., PM) trigger delayed effects potentially via separate mechanisms.
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Affiliation(s)
- Christina M Lamb
- Curriculum in Toxicology, University of North Carolina, Chapel Hill, North Carolina 27514, USA
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Carll AP, Haykal-Coates N, Winsett DW, Hazari MS, Nyska A, Richards JH, Willis MS, Costa DL, Farraj AK. Dietary salt exacerbates isoproterenol-induced cardiomyopathy in rats. Toxicol Pathol 2011; 39:925-37. [PMID: 21878552 DOI: 10.1177/0192623311416373] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Spontaneously hypertensive heart failure rats (SHHFs) take longer to develop compensated heart failure (HF) and congestive decompensation than common surgical models of HF. Isoproterenol (ISO) infusion can accelerate cardiomyopathy in young SHHFs, while dietary salt loading in hypertensive rats induces cardiac fibrosis, hypertrophy, and--in a minority-congestive HF. By combining ISO with dietary salt loading in young SHHFs, the authors sought a nonsurgical model that is more time--and resource-efficient than any of these factors alone. The authors hypothesized that salt loading would enhance ISO-accelerated cardiomyopathy, promoting fibrosis, hypertrophy, and biochemical characteristics of HF. SHHFs (lean male, 90d) were infused for 4 wk with ISO (2.5 mg/kg/day) or saline. After 2 wk of infusion, a 6-wk high-salt diet (4%, 6%, or 8% NaCl) was initiated. Eight percent salt increased heart weight, HF markers (plasma B-type natriuretic peptide, IL-6), lung lymphocytes, and indicators of lung injury and edema (albumin and protein) relative to control diet, while increasing urine pro-atrial natriuretic peptide relative to ISO-only. High salt also exacerbated ISO-cardiomyopathy and fibrosis. Thus, combining ISO infusion with dietary salt loading in SHHFs holds promise for a new rat HF model that may help researchers to elucidate HF mechanisms and unearth effective treatments.
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Affiliation(s)
- Alex P Carll
- Department of Environmental Sciences and Engineering, Gillings School of Global Public Health, University of North Carolina at Chapel Hill, North Carolina, USA
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Hazari MS, Haykal-Coates N, Winsett DW, Krantz QT, King C, Costa DL, Farraj AK. TRPA1 and sympathetic activation contribute to increased risk of triggered cardiac arrhythmias in hypertensive rats exposed to diesel exhaust. Environ Health Perspect 2011; 119:951-7. [PMID: 21377951 PMCID: PMC3223009 DOI: 10.1289/ehp.1003200] [Citation(s) in RCA: 107] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/10/2010] [Accepted: 03/04/2011] [Indexed: 05/20/2023]
Abstract
BACKGROUND Diesel exhaust (DE), which is emitted from on- and off-road sources, is a complex mixture of toxic gaseous and particulate components that leads to triggered adverse cardiovascular effects such as arrhythmias. OBJECTIVE We hypothesized that increased risk of triggered arrhythmias 1 day after DE exposure is mediated by airway sensory nerves bearing transient receptor potential (TRP) channels [e.g., transient receptor potential cation channel, member A1 (TRPA1)] that, when activated by noxious chemicals, can cause a centrally mediated autonomic imbalance and heightened risk of arrhythmia. METHODS Spontaneously hypertensive rats implanted with radiotelemeters were whole-body exposed to either 500 μg/m³ (high) or 150 μg/m³ (low) whole DE (wDE) or filtered DE (fDE), or to filtered air (controls), for 4 hr. Arrhythmogenesis was assessed 24 hr later by continuous intravenous infusion of aconitine, an arrhythmogenic drug, while heart rate (HR) and electrocardiogram (ECG) were monitored. RESULTS Rats exposed to wDE or fDE had slightly higher HRs and increased low-frequency:high-frequency ratios (sympathetic modulation) than did controls; ECG showed prolonged ventricular depolarization and shortened repolarization periods. Rats exposed to wDE developed arrhythmia at lower doses of aconitine than did controls; the dose was even lower in rats exposed to fDE. Pretreatment of low wDE-exposed rats with a TRPA1 antagonist or sympathetic blockade prevented the heightened sensitivity to arrhythmia. CONCLUSIONS These findings suggest that a single exposure to DE increases the sensitivity of the heart to triggered arrhythmias. The gaseous components appear to play an important role in the proarrhythmic response, which may be mediated by activation of TRPA1, and subsequent sympathetic modulation. As such, toxic inhalants may partly exhibit their toxicity by lowering the threshold for secondary triggers, complicating assessment of their risk.
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Affiliation(s)
- Mehdi S Hazari
- Environmental Public Health Division, U.S. Environmental Protection Agency, Research Triangle Park, North Carolina 27711, USA.
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Carll AP, Haykal-Coates N, Winsett DW, Rowan WH, Hazari MS, Ledbetter AD, Nyska A, Cascio WE, Watkinson WP, Costa DL, Farraj AK. Particulate matter inhalation exacerbates cardiopulmonary injury in a rat model of isoproterenol-induced cardiomyopathy. Inhal Toxicol 2010; 22:355-68. [PMID: 20121584 DOI: 10.3109/08958370903365692] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
Ambient particulate matter (PM) exposure is linked to cardiovascular events and death, especially among individuals with heart disease. A model of toxic cardiomyopathy was developed in Spontaneously Hypertensive Heart Failure (SHHF) rats to explore potential mechanisms. Rats were infused with isoproterenol (ISO; 2.5 mg/kg/day subcutaneous [sc]), a beta-adrenergic agonist, for 28 days and subsequently exposed to PM by inhalation. ISO induced tachycardia and hypotension throughout treatment followed by postinfusion decrements in heart rate, contractility, and blood pressures (systolic, diastolic, pulse), and fibrotic cardiomyopathy. Changes in heart rate and heart rate variability (HRV) 17 days after ISO cessation indicated parasympathetic dominance with concomitantly altered ventilation. Rats were subsequently exposed to filtered air or Harvard Particle 12 (HP12) (12 mg/m(3))--a metal-rich oil combustion-derived PM--at 18 and 19 days (4 h/day) after ISO infusion via nose-only inhalation to determine if cardio-impaired rats were more responsive to the effects of PM exposure. Inhalation of PM among ISO-pretreated rats significantly increased pulmonary lactate dehydrogenase, serum high-density lipoprotein (HDL) cholesterol, and heart-to-body mass ratio. PM exposure increased the number of ISO-pretreated rats that experienced bradyarrhythmic events, which occurred concomitantly with acute alterations of HRV. PM, however, did not significantly affect mean HRV in the ISO- or saline-pretreated groups. In summary, subchronic ISO treatment elicited some pathophysiologic and histopathological features of heart failure, including cardiomyopathy. The enhanced sensitivity to PM exposure in SHHF rats with ISO-accelerated cardiomyopathy suggests that this model may be useful for elucidating the mechanisms by which PM exposure exacerbates heart disease.
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Affiliation(s)
- Alex P Carll
- Environmental Sciences and Engineering, UNC Gillings School of Global Public Health, Chapel Hill, North Carolina, USA
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Farraj AK, Hazari MS, Haykal-Coates N, Lamb C, Winsett DW, Ge Y, Ledbetter AD, Carll AP, Bruno M, Ghio A, Costa DL. ST depression, arrhythmia, vagal dominance, and reduced cardiac micro-RNA in particulate-exposed rats. Am J Respir Cell Mol Biol 2010; 44:185-96. [PMID: 20378750 DOI: 10.1165/rcmb.2009-0456oc] [Citation(s) in RCA: 65] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023] Open
Abstract
Recently, investigators demonstrated associations between fine particulate matter (PM)-associated metals and adverse health effects. Residual oil fly ash (ROFA), a waste product of fossil fuel combustion from boilers, is rich in the transition metals Fe, Ni, and V, and when released as a fugitive particle, is an important contributor to ambient fine particulate air pollution. We hypothesized that a single-inhalation exposure to transition metal-rich PM will cause concentration-dependent cardiovascular toxicity in spontaneously hypertensive (SH) rats. Rats implanted with telemeters to monitor heart rate and electrocardiogram were exposed once by nose-only inhalation for 4 hours to 3.5 mg/m(3), 1.0 mg/m(3), or 0.45 mg/m(3) of a synthetic PM (dried salt solution), similar in composition to a well-studied ROFA sample consisting of Fe, Ni, and V. Exposure to the highest concentration of PM decreased T-wave amplitude and area, caused ST depression, reduced heart rate (HR), and increased nonconducted P-wave arrhythmias. These changes were accompanied by increased pulmonary inflammation, lung resistance, and vagal tone, as indicated by changes in markers of HR variability (increased root of the mean of squared differences of adjacent RR intervals [RMSSD], low frequency [LF], high frequency [HF], and decreased LF/HF), and attenuated myocardial micro-RNA (RNA segments that suppress translation by targeting messenger RNA) expression. The low and intermediate concentrations of PM had less effect on the inflammatory, HR variability, and micro-RNA endpoints, but still caused significant reductions in HR. In addition, the intermediate concentration caused ST depression and increased QRS area, whereas the low concentration increased the T-wave parameters. Thus, PM-induced cardiac dysfunction is mediated by multiple mechanisms that may be dependent on PM concentration and myocardial vulnerability (this abstract does not reflect the policy of the United States Environmental Protection Agency).
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Affiliation(s)
- Aimen K Farraj
- Environmental Public Health Division, United States Environmental Protection Agency, Research Triangle Park, NC 27711, USA.
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Hazari MS, Haykal-Coates N, Winsett DW, Costa DL, Farraj AK. A single exposure to particulate or gaseous air pollution increases the risk of aconitine-induced cardiac arrhythmia in hypertensive rats. Toxicol Sci 2009; 112:532-42. [PMID: 19748997 DOI: 10.1093/toxsci/kfp214] [Citation(s) in RCA: 42] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023] Open
Abstract
Epidemiological studies demonstrate an association between arrhythmias and air pollution. Aconitine-induced cardiac arrhythmia is widely used experimentally to examine factors that alter the risk of arrhythmogenesis. In this study, Wistar-Kyoto (WKY) and spontaneously hypertensive (SH) rats acutely exposed to synthetic residual oil fly ash (s-ROFA) particles (450 mug/m(3)) were "challenged" with aconitine to examine whether a single exposure could predispose to arrhythmogenesis. Separately, SH rats were exposed to varied particulate matter (PM) concentrations (0.45, 1.0, or 3.5 mg/m(3) s-ROFA), or the irritant gas acrolein (3 ppm), to better assess the generalization of this challenge response. Rather than directly cause arrhythmias, we hypothesized that inhaled air pollutants sensitize the heart to subsequent dysrhythmic stimuli. Twenty-four hour postexposure, urethane-anesthetized rats were monitored for heart rate (HR), electrocardiogram, and blood pressure (BP). SH rats had higher baseline HR and BP and significantly longer PR intervals, QRS duration, QTc, and JTc than WKY rats. PM exposure caused a significant increase in the PR interval, QRS duration, and QTc in WKY rats but not in SH rats. Heart rate variability was significantly decreased in WKY rats after PM exposure but increased in SH rats. Cumulative dose of aconitine that triggered arrhythmias in air-exposed SH rats was lower than WKY rats and even lower for each strain postexposure. SH rats exposed to varied concentrations of PM or acrolein developed arrhythmia at significantly lower doses of aconitine than controls; however, there was no PM concentration-dependent response. In conclusion, a single exposure to air pollution may increase the sensitivity of cardiac electrical conduction to disruption. Moreover, there seem to be host factors (e.g., cardiovascular disease) that increase vulnerability to triggered arrhythmias regardless of the pollutant or its concentration.
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Affiliation(s)
- Mehdi S Hazari
- Environmental Public Health Division, U.S. Environmental Protection Agency, 109 Alexander Drive, B143-01, Research Triangle Park, NC 27711, USA.
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Farraj AK, Haykal-Coates N, Winsett DW, Hazari MS, Carll AP, Rowan WH, Ledbetter AD, Cascio WE, Costa DL. Increased non-conducted P-wave arrhythmias after a single oil fly ash inhalation exposure in hypertensive rats. Environ Health Perspect 2009; 117:709-15. [PMID: 19479011 PMCID: PMC2685831 DOI: 10.1289/ehp.0800129] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/27/2008] [Accepted: 12/31/2008] [Indexed: 05/08/2023]
Abstract
BACKGROUND Exposure to combustion-derived fine particulate matter (PM) is associated with increased cardiovascular morbidity and mortality especially in individuals with cardiovascular disease, including hypertension. PM inhalation causes several adverse changes in cardiac function that are reflected in the electrocardiogram (ECG), including altered cardiac rhythm, myocardial ischemia, and reduced heart rate variability (HRV). The sensitivity and reliability of ECG-derived parameters as indicators of the cardiovascular toxicity of PM in rats are unclear. OBJECTIVE We hypothesized that spontaneously hypertensive (SH) rats are more susceptible to the development of PM-induced arrhythmia, altered ECG morphology, and reduced HRV than are Wistar Kyoto (WKY) rats, a related strain with normal blood pressure. METHODS We exposed rats once by nose-only inhalation for 4 hr to residual oil fly ash (ROFA), an emission source particle rich in transition metals, or to air and then sacrificed them 1 or 48 hr later. RESULTS ROFA-exposed SH rats developed non-conducted P-wave arrhythmias but no changes in ECG morphology or HRV. We found no ECG effects in ROFA-exposed WKY rats. ROFA-exposed SH rats also had greater pulmonary injury, neutrophil infiltration, and serum C-reactive protein than did ROFA-exposed WKY rats. CONCLUSIONS These results suggest that cardiac arrhythmias may be an early sensitive indicator of the propensity for PM inhalation to modify cardiovascular function.
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Affiliation(s)
- Aimen K Farraj
- Experimental Toxicology Division, National Health and Environmental Effects Research Laboratory, U.S. Environmental Protection Agency, Research Triangle Park, North Carolina 27711, USA.
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Hazari MS, Haykal-Coates N, Winsett DW, Costa DL, Farraj AK. Continuous Electrocardiogram Reveals Differences in the Short-Term Cardiotoxic Response of Wistar-Kyoto and Spontaneously Hypertensive Rats to Doxorubicin. Toxicol Sci 2009; 110:224-34. [DOI: 10.1093/toxsci/kfp092] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
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LaGier AJ, Manzo ND, Carll AP, Jaskot RH, Slade R, Richards JH, Winsett DW, Farraj AK, Dye JA. A hyperlipidemic rabbit model provides new insights into pulmonary zinc exposure effects on cardiovascular health. Cardiovasc Toxicol 2008; 8:195-206. [PMID: 18953671 DOI: 10.1007/s12012-008-9028-9] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/20/2008] [Accepted: 10/06/2008] [Indexed: 10/21/2022]
Abstract
This study ascertains the effects of zinc, a major component of particulate matter, on pulmonary and systemic endpoints using hyperlipidemic rabbits to model diet-induced human atherosclerosis. New Zealand White rabbits were fed a normal or cholesterol-enriched diet and then were intratracheally instilled 1x/week for 4 weeks with saline or 16 microg/kg of zinc, equal parts sulfate and oxide. Physiologic responses, blood after each exposure, and terminal bronchoalveolar lavage (BAL) were assessed. Rabbits fed a cholesterol-rich diet developed hyperlipidemia and had consistently higher circulating leukocyte counts than rabbits fed normal chow. Within minutes after zinc instillation, saturation of peripheral oxygen was decreased in hyperlipidemic rabbits and heart rate was increased in hyperlipidemic rabbits with total serum cholesterol levels greater than 200 mg/dl. Total circulating leukocytes levels were increased 24 h after the first zinc instillation, but upon repeated exposures this effect was attenuated. After repeated zinc exposures, BAL fluid (BALF) N-acetylglucosaminidase activity was increased regardless of hyperlipidemic state. Hyperlipidemic rabbits had an increase in BALF-oxidized glutathione and a decrease in serum nitrite. The study elucidates mechanisms by which the zinc metal component of PM drives cardiovascular health effects, as well as the possible susceptibility induced by hyperlipidemia. Furthermore, the study exemplifies the benefits of monitoring circulatory physiology during exposure as well as after exposure.
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Affiliation(s)
- Adriana J LaGier
- Experimental Toxicology Division, National Health and Environmental Effects Research Laboratory, Office of Research and Development, U.S. Environmental Protection Agency, Research Triangle Park, NC 27711, USA.
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Wichers LB, Nolan JP, Winsett DW, Ledbetter AD, Kodavanti UP, Schladweiler MCJ, Costa DL, Watkinson WP. Effects of Instilled Combustion-Derived Particles in Spontaneously Hypertensive Rats. Part I: Cardiovascular Responses. Inhal Toxicol 2008; 16:391-405. [PMID: 15204755 DOI: 10.1080/08958370490439696] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
Abstract
Epidemiological studies have reported statistically significant associations between the levels of ambient particulate matter (PM) and the incidence of morbidity and mortality, particularly among persons with cardiopulmonary disease. While similar effects have been demonstrated in animals, the mechanism(s) by which these effects are mediated are unresolved. To further investigate this phenomenon, the cardiovascular and thermoregulatory effects of an oil combustion-derived PM (HP-12) were examined in spontaneously hypertensive (SH) rats. The particle used in this study had considerably fewer water-soluble metals than the residual oil fly ash (ROFA) particles widely used in previous animal toxicity studies, with Zn and Ni constituting the primary water-leachable elements in HP-12. Rats were surgically implanted with radiotelemeters capable of continuously monitoring electrocardiogram (ECG), heart rate (HR), systemic arterial blood pressure (BP), and core temperature (T(co)). Animals were divided into four dose groups and were administered one of four doses of HP-12 suspended in saline vehicle (0.00, 0.83, 3.33, 8.33 mg/kg; control, low, mid, and high dose, respectively) via intratracheal instillation (IT). Telemetered rats were monitored continuously for up to 7 days post-IT, and were sacrificed 4 or 7 days post-IT. Exposures to mid- and high-dose HP-12 induced large decreases in HR (decreasing 30-120 bpm), BP (decreasing 20-30 mmHg), and T(co) (decreasing 1.2-2.6 degrees C). The decreases in HR and BP were most pronounced at night and did not return to pre-IT values until 72 and 48 h after dosing, respectively. ECG abnormalities (rhythm disturbances, bundle branch block) were observed primarily in the high-dose group. This study demonstrates substantial dose-related deficits in cardiac function in SH rats after IT exposure to a low-metal content, combustion-derived particle.
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Affiliation(s)
- L B Wichers
- Department of Environmental Sciences and Engineering, School of Public Health, University of North Carolina, Chapel Hill, USA
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Vinegar A, Winsett DW, Andersen ME, Conolly RB. Use of a Physiologically Based Pharmacokinetic Model and Computer Simulation for Retrospective Assessment of Exposure to Volatile Toxicants. Inhal Toxicol 2008. [DOI: 10.3109/08958379009145249] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
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Pritchard RJ, Ghio AJ, Lehmann JR, Winsett DW, Tepper JS, Park P, Gilmour MI, Dreher KL, Costa DL. Oxidant Generation and Lung Injury after Particulate Air Pollutant Exposure Increase with the Concentrations of Associated Metals. Inhal Toxicol 2008. [DOI: 10.3109/08958379609005440] [Citation(s) in RCA: 172] [Impact Index Per Article: 10.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
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22
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Hazari MS, Rowan WH, Winsett DW, Ledbetter AD, Haykal-Coates N, Watkinson WP, Costa DL. Potentiation of pulmonary reflex response to capsaicin 24h following whole-body acrolein exposure is mediated by TRPV1. Respir Physiol Neurobiol 2007; 160:160-71. [PMID: 17950047 DOI: 10.1016/j.resp.2007.09.003] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2007] [Revised: 09/06/2007] [Accepted: 09/11/2007] [Indexed: 11/26/2022]
Abstract
Pulmonary C-fibers are stimulated by irritant air pollutants producing apnea, bronchospasm, and decrease in HR. Chemoreflex responses resulting from C-fiber activation are sometimes mediated by TRPV1 and release of substance P. While acrolein has been shown to stimulate C-fibers, the persistence of acrolein effects and the role of C-fibers in these responses are unknown. These experiments were designed to determine the effects of whole-body acrolein exposure and pulmonary chemoreflex response post-acrolein. Rats were exposed to either air or 3 ppm acrolein for 3 h while ventilatory function and HR were measured; 1-day later response to capsaicin challenge was measured in anesthetized rats. Rats experienced apnea and decrease in HR upon exposure to acrolein, which was not affected by either TRPV1 antagonist or NK(1)R antagonist pretreatment. Twenty-four hours later, capsaicin caused apnea and bronchoconstriction in control rats, which was potentiated in rats exposed to acrolein. Pretreatment with TRPV1 antagonist or NK(1)R antagonist prevented potentiation of apneic response and bronchoconstriction 24h post-exposure. These data suggest that although potentiation of pulmonary chemoreflex response 24h post-acrolein is mediated by TRPV1 and release of substance P, cardiopulmonary inhibition during whole-body acrolein exposure is mediated through other mechanisms.
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Affiliation(s)
- Mehdi S Hazari
- Curriculum in Toxicology, University of North Carolina, Chapel Hill, NC 27599-7270, United States.
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Wiester MJ, Costa DL, Tepper JS, Winsett DW, Slade R. Agonist-mediated airway challenge: cardiopulmonary interactions modulate gas exchange and recovery. Respir Physiol Neurobiol 2005; 145:183-99. [PMID: 15705534 DOI: 10.1016/j.resp.2004.02.006] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 02/17/2004] [Indexed: 11/17/2022]
Abstract
Diverse agonists used for airway challenges produce a stereotypic sequence of immediate functional responses (e.g., bronchoconstriction, gas trapping, hypoxemia, etc.) at the time such reactions are triggered. The reaction incorporates both pulmonary and cardiac changes that clearly interact in an orchestrated fashion taking the subject (or animal model) through the response generally to ultimate recovery. We hypothesize that despite differences in the initiation of the response, diverse airway provocations lead to a cascade of events that converge through a common physiologic pathway. To better understand the sequence of events and the counterbalanced cardiopulmonary responses, we examined histamine, methacholine, and ovalbumin (OVA) challenges in the awake guinea pig model and assessed ventilatory and breathing mechanics in the context of associated cardiac parameters. With the histamine response as the prototype, we evaluated the role of beta-adrenoreceptors using propranolol (1.0-10 mg/kg i.p.) and found that beta-adrenoreceptors are critical in reducing challenge-induced gas trapping in the lungs. The disposition of the circulatory response to agonist challenge (the OVA model) was reflected in a significant absolute shunting of blood through poorly ventilated regions of the lung. The methacholine challenge revealed that gasping enhanced lung inflation and reversed the diminished Pa(O2). Moreover, beta-sympathetic function was critical to recovery. Collectively, the response profiles of these disparate models of airway challenge suggest a highly integrated balance to maintain gas exchange among the pulmonary airways and vasculature, modulated in recovery by beta-adrenoreceptors.
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Affiliation(s)
- Mildred J Wiester
- Experimental Toxicology Division, National Health and Environmental Effects Research Laboratory, Office of Research Development, U.S. Environmental Protection Agency, B 143-01 Research Triangle Park, NC 27711, USA
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Wichers LB, Nolan JP, Winsett DW, Ledbetter AD, Kodavanti UP, Schladweiler MCJ, Costa DL, Watkinson WP. Effects of instilled combustion-derived particles in spontaneously hypertensive rats. Part II: Pulmonary responses. Inhal Toxicol 2004; 16:407-19. [PMID: 15204756 DOI: 10.1080/08958370490439704] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
Abstract
A consistent association between exposure to high concentrations of ambient particulate matter (PM) and excess cardiopulmonary-related morbidity and mortality has been observed in numerous epidemiological studies, across many different geographical locations. To elicit a similar response in a controlled laboratory setting, spontaneously hypertensive rats were exposed to an oil combustion-derived PM (HP-12) and monitored for changes in pulmonary function and indices of pulmonary injury. Rats were implanted with radiotelemeters to monitor electrocardiogram, heart rate, systemic arterial blood pressure, core temperature, and activity. Animals were divided into four groups and exposed via intratracheal instillation (IT) to suspensions of HP-12 (0.0, 0.83, 3.33, and 8.33 mg/kg; control, low, mid, and high dose, respectively) in saline vehicle. Telemetered rats were monitored continuously for 4-7 days post-IT and pulmonary function was examined using a whole-body plethysmograph system for 6 h/day on post-IT days 1-7. At 24, 96, and 192 h post-IT, bronchoalveolar lavage fluid (BALF) was obtained from subsets of nontelemetered animals in order to assess the impact of HP-12 on biochemical indices of pulmonary inflammation and injury. Immediate dose-related changes in pulmonary function were observed after HP-12 exposure, consisting of decreases in tidal volume (decreasing 12-41%) and increases in breathing frequency (increasing 52-103%), minute ventilation (increasing 12-25%), and enhanced pause (increasing 113-187%). These functional effects were resolved by 7 days post-IT, although some average BALF constituents remained elevated through day 7 for mid- and high-dose groups when compared to those of the saline-treated control group. This study demonstrates significant deficits in pulmonary function, along with significant increases in BALF indices of pulmonary inflammation and injury in SH rats after IT exposure to HP-12.
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Affiliation(s)
- L B Wichers
- Department of Environmental Sciences and Engineering, School of Public Health, University of North Carolina, Chapel Hill, USA
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25
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Gardner SY, McGee JK, Kodavanti UP, Ledbetter A, Everitt JI, Winsett DW, Doerfler DL, Costa DL. Emission-particle-induced ventilatory abnormalities in a rat model of pulmonary hypertension. Environ Health Perspect 2004; 112:872-878. [PMID: 15175175 PMCID: PMC1242015 DOI: 10.1289/ehp.6583] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
Preexistent cardiopulmonary disease in humans appears to enhance susceptibility to the adverse effects of ambient particulate matter. Previous studies in this laboratory have demonstrated enhanced inflammation and mortality after intratracheal instillation (IT) and inhalation (INH) of residual oil fly ash (ROFA) in a rat model of pulmonary hypertension induced by monocrotaline (MCT). The present study was conducted to examine the effects of ROFA in this model on ventilatory function in unanesthetized, unrestrained animals. Sixty-day-old male CD rats were injected with MCT (60 mg/kg) or vehicle (VEH) intraperitoneally 10 days before IT of ROFA (8.3 mg/kg) or saline (SAL) (control) or nose-only INH of ROFA [15 mg/m3 for 6 hr on 3 consecutive days or air (control)]. At 24 and 72 hr after exposure, rats were studied individually in a simultaneous gas uptake/whole-body plethysmograph. Lungs were removed at 72 hr for histology. Pulmonary test results showed that tidal volume (VT) decreased 24 hr after IT of ROFA in MCT-treated rats. Breathing frequency, minute volume (VE), and the ventilatory equivalent for oxygen increased in MCT- and VEH-treated rats 24 hr after IT or INH of ROFA and remained elevated 72 hr post-IT. O2 uptake (VO2) decreased after IT of ROFA in MCT-treated rats. Carbon monoxide uptake decreased 24 hr after IT of ROFA, returning to control values in VEH-treated rats but remaining low in MCT-treated rats 72 hr post-IT. ROFA exposure induced histologic changes and abnormalities in several ventilatory parameters, many of which were enhanced by MCT treatment.
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Affiliation(s)
- Sarah Y Gardner
- College of Veterinary Medicine, North Carolina State University, 4700 Hillsborough Street, Raleigh, NC 27606, USA.
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Singh P, Daniels M, Winsett DW, Richards J, Doerfler D, Hatch G, Adler KB, Gilmour MI. Phenotypic comparison of allergic airway responses to house dust mite in three rat strains. Am J Physiol Lung Cell Mol Physiol 2003; 284:L588-98. [PMID: 12618421 DOI: 10.1152/ajplung.00287.2002] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Brown Norway (BN) rats develop a robust response to antigens in the lung, characterized by a large increase in allergen-specific immune function and pulmonary eosinophilia. The objective of this study was to investigate alternative models by determining whether other rat strains could be sensitized to house dust mite (HDM) antigen and whether the allergic disease process could be worsened with repeated allergen exposure. In general, BN rats sensitized by either subcutaneous or intratracheal routes exhibited increased pulmonary allergy compared with Sprague-Dawley (SD) and Lewis (L) rats. Multiple intratracheal allergen exposures incrementally increased HDM-specific immune function in BN rats but progressively decreased eosinophil recruitment and markers of lung injury. SD rats had more moderate responses, whereas L rats were relatively unresponsive. Because BN rats developed stronger clinical hallmarks of allergic asthma under various immunization regimes compared with SD and L rats, we conclude that the BN is the most appropriate strain for studying allergic asthma-like responses in rats. Phenotypic differences in response to HDM were associated with differences in the Th1/Th2 cytokine balance and antioxidant capacity.
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Affiliation(s)
- Pramila Singh
- North Carolina State University, College of Veterinary Medicine, Raleigh 27606, USA
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Wiester MJ, Winsett DW, Richards JH, Doerfler DL, Costa DL. Partitioning of benzene in blood: influence of hemoglobin type in humans and animals. Environ Health Perspect 2002; 110:255-261. [PMID: 11882476 PMCID: PMC1240765 DOI: 10.1289/ehp.02110255] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
Abstract
Earlier studies have shown that air/blood partition coefficients (PCs) for many volatile organic chemicals (VOCs) are much higher in rat blood than in human blood. It has been suggested that the discrepancy could be attributed to the fact that hemoglobin (Hb) in rat blood exists in a quasi-crystalline form of hydrophobicity greater than that of normal human Hb (HbA) and thus has a higher carrying capacity for VOCs. In the present study, we used benzene as a prototypic VOC to examine its relative partitioning into human and animal blood. Additionally, we sought to ascertain whether the water-insoluble form of hemoglobin (HbS) found in subjects with homozygous sickle cell (SC) disease has a greater VOC-carrying capacity than does HbA blood. At a low-O(2) tension, HbS switches to water-insoluble polymers, which physically deforms the red blood cells (RBCs) to the sickle shape. We equilibrated HbA, HbS, Hartley guinea pig, CD1 mouse, and rat (F-344, Wistar, and Sprague-Dawley) blood and their respective fractions with benzene vapor (80 or 400 ppm) for 3 hr at 37 degrees C in air-tight vials. We introduced benzene vapor into the vial head space that contained air or respiratory mixtures of venous-type (low-O(2)) or arterial-type (high-O(2)) gases. The blood measurements included the PC, Hb, partial pressures of O(2)(pO(2)) and CO(2)(pCO(2), pH, and percentage of SCs. The benzene concentration had no effect on these parameters, and the high- and low-O(2) gas mixtures produced the expected changes in pO(2), pCO(2), and pH. At equilibrium, the low-O(2) HbS blood had approximately 85% SCs compared with roughly 15% with air or high-O(2) gas. PCs for rat and mouse blood were about 100% higher than those for human and guinea pig blood, but the PC for deoxygenated HbS blood was only slightly higher than that for HbA or oxygenated HbS blood. Benzene showed higher affinities for RBCs in the deoxygenated HbS, rat, and mouse blood and higher affinity for plasma in the guinea pig blood. There was no evidence of disproportionate partitioning of benzene into oxygenated HbS or into HbA blood forms. These data suggest that the water solubility of Hb alone appears to have little effect on the VOC-carrying capacity of blood and that the influence of species is large in comparison. These latter differences in partitioning may depend on the number of hydrophobic sites on the surface of the plasma/heme proteins and thus be unique to the species.
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Affiliation(s)
- Mildred J Wiester
- Office of Research and Development, National Health and Environmental Effects Research Laboratory, U.S. Environmental Protection Agency, Research Triangle Park, NC 27711, USA.
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Abstract
We have recently demonstrated that pulmonary exposure to residual oil fly ash (ROFA) resulted in enhanced sensitization to house dust mite (HDM) and augmented the development of allergic lung disease after allergen challenge. This effect was associated with increased tumor necrosis factor alpha (TNF-alpha), a macrophage- and epithelial cell-derived cytokine that promotes granulocyte migration to the lung. The present study examined whether exogenous administration of TNF-alpha enhances sensitization to HDM. One day prior to pulmonary sensitization with 10 microg HDM (5 microg each on days 1 and 3), female Brown Norway rats were instilled via the trachea with either 2.0 microg recombinant rat TNF-alpha, 2.0 microg bovine serum albumin (BSA), or 1,000 microg ROFA, and were challenged with 10 microg HDM 14 days later. Antigen-induced immediate bronchoconstriction responses, antigen-specific immunoglobulin E (IgE) titers, lymphocyte proliferation, (cytokines (TNF-alpha and interleukin [IL]-13), and eosinophils were elevated in rats treated with ROFA or TNF-alpha compared with BSA-treated controls after HDM challenge. Intratracheal administration of anti-TNF-alpha monoclonal antibody during ROFA exposure did not reduce ROFA-enhanced lymphocyte proliferation or IgE titers, but had a trend for reduced pulmonary inflammation. This study demonstrates that TNF-alpha has similar adjuvant activity as ROFA, but other factors may fulfill this function when TNF-alpha activity is blocked.
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Affiliation(s)
- A L Lambert
- University of North Carolina at Chapel Hill, USA
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Dye JA, Lehmann JR, McGee JK, Winsett DW, Ledbetter AD, Everitt JI, Ghio AJ, Costa DL. Acute pulmonary toxicity of particulate matter filter extracts in rats: coherence with epidemiologic studies in Utah Valley residents. Environ Health Perspect 2001; 109 Suppl 3:395-403. [PMID: 11427389 PMCID: PMC1240557 DOI: 10.1289/ehp.01109s3395] [Citation(s) in RCA: 80] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/22/2023]
Abstract
Epidemiologic reports by C.A. Pope III et. al. demonstrated that in the Utah Valley, closure of an open-hearth steel mill over the winter of 1987 was associated with reductions in respiratory disease and related hospital admissions in valley residents. To better examine the relationship between plant-associated changes in ambient particulate matter (PM) and respiratory health effects, we obtained total suspended particulate filters originally collected near the steel mill during the winter of 1986 (before closure), 1987 (during closure), and 1988 (after plant reopening). PM subcomponents were water-extracted from these filters and Sprague-Dawley rats were intratracheally instilled with equivalent masses of extract. Data indicated that 24 hr later, rats exposed to 1986 or 1988 extracts developed significant pulmonary injury and neutrophilic inflammation. Additionally, 50% of rats exposed to 1986 or 1988 extracts had increased airway responsiveness to acetylcholine, compared to 17 and 25% of rats exposed to saline or the 1987 extract, respectively. By 96 hr, these effects were largely resolved except for increases in lung lavage fluid neutrophils and lymphocytes in 1986 extract-exposed rats. Analogous effects were observed with lung histologic assessment. Extract analysis using inductively coupled plasma-mass spectroscopy demonstrated in all three extracts nearly 70% of the mass appeared to be sodium-based salts derived from the glass filter matrix. Interestingly, relative to the 1987 extract, the 1986/1988 extracts contained more sulfate, cationic salts (i.e., calcium, potassium, magnesium), and certain metals (i.e., copper, zinc, iron, lead, strontium, arsenic, manganese, nickel). Although total metal content was (3/4) 1% of the extracts by mass, the greater quantity detected in the 1986 and 1988 extracts suggests metals may be important determinants of the pulmonary toxicity observed. In conclusion, the pulmonary effects induced by exposure of rats to water-based extracts of local ambient PM filters were in good accord with the cross-sectional epidemiologic reports of adverse respiratory health effects in Utah Valley residents.
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Affiliation(s)
- J A Dye
- U.S. Environmental Protection Agency, Office of Research and Development, National Health and Environmental Effects Research Laboratory, Research Triangle Park, NC 27711, USA
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Wiester MJ, Winsett DW, Richards JH, Jackson MC, Crissman KM, Costa DL. Ozone adaptation in mice and its association with ascorbic acid in the lung. Inhal Toxicol 2000; 12:577-90. [PMID: 10880145 DOI: 10.1080/08958370050030958] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/17/2022]
Abstract
We have previously shown that ozone (O(3)) adaptation occurred in rats after daily exposure to an "urban-type" concentration. The adaptation was positively associated with an excess of ascorbic acid (AA) in bronchoalveolar lavage fluid (BALF), suggesting that AA may play a role in the adaptation mechanism. This relationship was not seen at higher and more toxic exposures. The present work exposed mice to low and high levels of O(3) to see if the adaptation-AA relationship is common among rodent species. Male CD-1 mice were studied during repeated 6-h/day exposures to 0.0 or 0.25 ppm O(3) for 10 days and 10 days of recovery in air (experiment 1) and to 0.0, 0.5, or 1.0 ppm O(3) for 5 days (experiment 2). Approximately 20 h after each daily exposure, groups of mice were randomly selected from each concentration type and examined for patterns of response. They were anesthetized (urethane, ip), intubated, and the lungs were lavaged with 37 degrees C saline. BALF was assayed for cells, cell differential, protein, albumin, lactate dehydrogenase, lysozymes, N-acetyl-beta-D-glucosaminidase, gamma-glutamyl transferase, uric acid, glutathione, and AA. Body weight and total lung capacity were also measured. Mice from experiment 1 (10/exposure) were tested for adaptation on day 12 by challenging them with 1.0 ppm O(3) for 6 h and collecting BALF 20 h later. In experiment 2, adaptation was assessed by evaluating the attenuation in response to continued exposure. There was only minimal response to the daily O(3) exposures in experiment 1 except for AA, which was significantly increased in BALF by day 3 and remained elevated well into the recovery period. The O(3)-preexposed mice demonstrated adaptation when compared to their O(3)-naive counterparts. Daily exposure to 1. 0 ppm O(3) in experiment 2 caused weight loss and changes in BALF consistent with toxicity, and neither adaptation nor an excess quantity of AA was seen. The findings in mice were in agreement with those seen in rats and suggest that there may be a common O(3) adaptation mechanism among rodents that involves the regulation of AA in lung lining fluid.
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Affiliation(s)
- M J Wiester
- U.S. Environmental Protection Agency, National Health and Environmental Effects Research Laboratory, Experimental Toxicology Division, Pulmonary Toxicology Branch, Research Triangle Park, NC 27711, USA.
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Kodavanti UP, Jackson MC, Ledbetter AD, Starcher BC, Evansky PA, Harewood A, Winsett DW, Costa DL. The Combination of Elastase and Sulfur Dioxide Exposure Causes COPD-Like Lesions in the Rat. Chest 2000. [DOI: 10.1378/chest.117.5_suppl_1.299s] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/01/2022] Open
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Kodavanti UP, Schladweiler MC, Ledbetter AD, Watkinson WP, Campen MJ, Winsett DW, Richards JR, Crissman KM, Hatch GE, Costa DL. The spontaneously hypertensive rat as a model of human cardiovascular disease: evidence of exacerbated cardiopulmonary injury and oxidative stress from inhaled emission particulate matter. Toxicol Appl Pharmacol 2000; 164:250-63. [PMID: 10799335 DOI: 10.1006/taap.2000.8899] [Citation(s) in RCA: 117] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
Cardiovascular disease is considered a probable risk factor of particulate matter (PM)-related mortality and morbidity. It was hypothesized that rats with hereditary systemic hypertension and underlying cardiac disease would be more susceptible than healthy normotensive rats to pulmonary injury from inhaled residual oil fly ash (ROFA) PM. Eight spontaneously hypertensive (SH) and eight normotensive Wistar-Kyoto (WKY) rats (12-13 weeks old) were implanted with radiotelemetry transmitters on Day -10 for measurement of electrocardiographic (ECG) waveforms. These and other nonimplanted rats were exposed to filtered air or ROFA (containing leachable toxic levels of metals) on Day 0 by nose-only inhalation (ROFA, 15 mg/m(3) x 6 h/day x 3 days). ECGs were monitored during both exposure and nonexposure periods. At 0 or 18 h post-ROFA exposure, rats were assessed for airway hyperreactivity, pulmonary and cardiac histological lesions, bronchoalveolar lavage fluid (BALF) markers of lung injury, oxidative stress, and cytokine gene expression. Comparisons were made in two areas: (1) underlying cardiopulmonary complications of control SH rats in comparison to control WKY rats; and (2) ROFA-induced cardiopulmonary injury/inflammation and oxidative burden. With respect to the first area, control air-exposed SH rats had higher lung and left ventricular weights when compared to age-matched WKY rats. SH rats had hyporeactive airways to acetylcholine challenge. Lung histology revealed the presence of activated macrophages, neutrophils, and hemorrhage in control SHrats. Consistently, levels of BALF protein, macrophages, neutrophils, and red blood cells were also higher in SH rats. Thiobarbituric acid-reactive material in the BALF of air-exposed SH rats was significantly higher than that of WKY rats. Lung inflammation and lesions were mirrored in the higher basal levels of pulmonary cytokine mRNA expression. Cardiomyopathy and monocytic cell infiltration were apparent in the left ventricle of SH rats, along with increased cytokine expression. ECG demonstrated a depressed ST segment area in SH rats. With regard to the second area of comparison (ROFA-exposed rats), pulmonary histology indicated a slightly exacerbated pulmonary lesions including inflammatory response to ROFA in SH rats compared to WKY rats and ROFA-induced increases in BALF protein and albumin were significantly higher in SH rats than in WKY rats. In addition, ROFA caused an increase in BALF red blood cells in SH rats, indicating increased hemorrhage in the alveolar parenchyma. The number of alveolar macrophages increased more dramatically in SH rats following ROFA exposure, whereas neutrophils increased similarly in both strains. Despite greater pulmonary injury in SH rats, ROFA-induced increases in BALF GSH, ascorbate, and uric acid were attenuated when compared to WKY rats. ROFA inhalation exposure was associated with similar increases in pulmonary mRNA expression of IL-6, cellular fibronectin, and glucose-6-phosphate dehydrogenase (relative to that of beta-actin) in both rat strains. The expression of MIP-2 was increased in WKY but attenuated in SH rats. Thus, SH rats have underlying cardiac and pulmonary complications. When exposed to ROFA, SH rats exhibited exacerbated pulmonary injury, an attenuated antioxidant response, and acute depression in ST segment area of ECG, which is consistent with a greater susceptibility to adverse health effects of fugitive combustion PM. This study shows that the SH rat is a potentially useful model of genetically determined susceptibility with pulmonary and cardiovascular complications.
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Affiliation(s)
- U P Kodavanti
- Pulmonary Toxicology Branch, U.S. Environmental Protection Agency, Research Triangle Park, North Carolina, 27711, USA
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Kodavanti UP, Jackson MC, Ledbetter AD, Starcher BC, Evansky PA, Harewood A, Winsett DW, Costa DL. The combination of elastase and sulfur dioxide exposure causes COPD-like lesions in the rat. Chest 2000; 117:299S-302S. [PMID: 10843962] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/16/2023] Open
Affiliation(s)
- U P Kodavanti
- Pulmonary Toxicology Branch, Experimental Toxicology Division, National Health and Environment Effects Research Laboratory, United States Environmental Protection Agency, Research Triangle Park, NC 27711, USA
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Lambert AL, Dong W, Winsett DW, Selgrade MK, Gilmour MI. Residual oil fly ash exposure enhances allergic sensitization to house dust mite. Toxicol Appl Pharmacol 1999; 158:269-77. [PMID: 10438660 DOI: 10.1006/taap.1999.8709] [Citation(s) in RCA: 55] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Epidemiological studies have shown an association between elevated levels of particulate matter air pollution and increased morbidity and hospital visits in asthmatics. Residual oil fly ash (ROFA) is a primary combustion particle containing sulfate and metals such as vanadium, nickel, and iron. In this study the effect of ROFA on sensitization to house dust mite (HDM) was examined in a Brown Norway rat model of pulmonary allergy. Rats were instilled via the trachea with 200 or 1000 micrograms ROFA 3 days prior to local sensitization with 10 micrograms HDM and were challenged with 10 micrograms HDM 14 days later. Immunological endpoints were examined at 2, 7, and 14 days after sensitization and at 2 and 7 days after challenge (16 and 21 days post-sensitization, respectively). Antigen-specific immunoglobulin E and associated immediate bronchoconstriction responses to antigen challenge were increased in the ROFA-treated groups compared with the HDM control group. Lymphocyte proliferation to antigen was enhanced at Days 7 and 21 in the bronchial lymphocytes of ROFA-treated groups. Bronchoalveolar lavage fluid (BALF) eosinophil numbers and lactate dehydrogenase were significantly increased in the 1000 micrograms ROFA group at Days 2 and 16, BALF total proteins were elevated at Days 2 and 7 in both ROFA-treated groups, and BALF interleukin (IL)-10 was elevated in the 1000 micrograms ROFA group at Day 2. These results suggest that ROFA has an adjuvant effect on sensitization to HDM.
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Affiliation(s)
- A L Lambert
- Curriculum in Toxicology, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, 27599, USA
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Lambert AL, Winsett DW, Costa DL, Selgrade MK, Gilmour MI. Transfer of allergic airway responses with serum and lymphocytes from rats sensitized to dust mite. Am J Respir Crit Care Med 1998; 157:1991-9. [PMID: 9620937 DOI: 10.1164/ajrccm.157.6.9704057] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
Abstract
House dust mite (HDM) antigen is one of the most common allergens associated with extrinsic asthma. In a model of allergic lung disease, Brown Norway (BN) rats sensitized to HDM with alum and Bordetella pertussis adjuvants produce high levels of IgE antibody and experience bronchoconstriction, increased airway hyperresponsiveness (AHR) to acetylcholine (ACh), and pulmonary inflammation after antigen challenge. The purpose of this study was to determine whether these asthmatic symptoms could be transferred from sensitized animals to naive recipients via humoral or cellular factors. Syngeneic recipient rats were injected (intraperitoneally with 4 x 10(7) cells (precultured overnight with either HDM or bovine serum albumin [BSA]) from lymph nodes of sensitized or control rats, respectively. Other groups received a tail-vein injection of serum from either HDM-sensitized or control rats. Antigen challenge in rats injected with sensitized cells caused increases in pulmonary inflammation and in AHR, but no changes in immediate bronchoconstriction as compared with control recipients. Antigen challenge in serum recipients resulted in immediate bronchoconstriction but had no effect on AHR or on pulmonary inflammation. These data show that immune-mediated lung inflammation and AHR are promoted by antigen-specific lymphocytes, whereas immediate allergic responses are caused by serum factors.
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Affiliation(s)
- A L Lambert
- School of Public Health, Center for Environmental Medicine and Lung Biology, University of North Carolina, Chapel Hill, NC, USA
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Schulman SR, Canada AT, Fryer AD, Winsett DW, Costa DL. Airway hyperreactivity produced by short-term exposure to hyperoxia in neonatal guinea pigs. Am J Physiol 1997; 272:L1211-6. [PMID: 9227525 DOI: 10.1152/ajplung.1997.272.6.l1211] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
Airway hyperreactivity is recognized as one of the long-term sequelae of bronchopulmonary dysplasia (BPD). Due to the improved care and prognosis of very low-birth weight infants, the incidence of BPD is increasing. There are data that suggest the increased survival of premature infants may be associated with the observed increased incidence of childhood asthma. The hyperoxia received as part of the treatment of respiratory distress syndrome is believed to be partly if not completely responsible for BPD. To gain insight into the potential role that hyperoxia might play in producing airway hyperreactivity, 4-day-old guinea pig pups were exposed to 70% oxygen or air for 96 h, and airway responsiveness to acetylcholine (ACh) was assessed both 2 and 9 days after the completion of the hyperoxia exposures. Unlike ozone, the mechanism for the persistently increased airway reactivity is not related either to the inhibition of neuronal acetylcholinesterase or inhibition of the neuronal M2 muscarinic receptor. A difference in antioxidant protection did not account for the increased response of the neonatal guinea pigs compared with hyperoxia-exposed rat pups. These data support the usefulness of the neonatal guinea pig as a model to study the mechanism responsible for hyperoxia-induced airway hyperreactivity.
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Affiliation(s)
- S R Schulman
- Department of Anesthesiology, Duke University Medical Center, Durham, North Carolina 27710, USA
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Gavett SH, Madison SL, Dreher KL, Winsett DW, McGee JK, Costa DL. Metal and sulfate composition of residual oil fly ash determines airway hyperreactivity and lung injury in rats. Environ Res 1997; 72:162-172. [PMID: 9177658 DOI: 10.1006/enrs.1997.3732] [Citation(s) in RCA: 81] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/22/2023]
Abstract
The biological effects of particulate matter (PM) deposition in the airways may depend on aqueousleachable chemical constituents of the particles. The effects of two residual oil fly ash (ROFA) PM samples of equivalent diameters but different metal and sulfate contents on pulmonary responses in Sprague-Dawley rats were investigated. ROFA sample 1 (R1) had approximately twice as much saline-leachable sulfate, nickel, and vanadium, and 40 times as much iron as ROFA sample 2 (R2), while R2 had a 31-fold higher zinc content. Four groups of rats were intratracheally instilled with a suspension of 2.5 mg R2 in 0.3 ml saline (R2), the supernatant of R2 (R2s), the supernatant of 2.5 mg R1 (R1s), or saline only. By 4 days after instillation, 4 of 24 rats treated with R2s or R2 had died, compared with non treated with R1s or saline, and pathological indices were greater in both R2 groups compared with the R1s group. In surviving rats, baseline pulmonary function parameters and airway hyperreactivity to acetylcholine challenge were significantly worse in R2 and R2s groups than in the R1s group. Numbers of bronchoalveolar lavage neutrophils, but not other inflammatory cells or biochemical parameters of lung injury, were greater in both R2 groups compared with the R1s group. These results reinforce the hypothesis that the composition of soluble metals and sulfate leached from ROFA, an emission source particle, is critical in the development of airway hyperreactivity and lung injury.
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Affiliation(s)
- S H Gavett
- Pulmonary Toxicology Branch, U.S. Environmental Protection Agency, Research Triangle Park, North Carolina 27711, USA
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Wiester MJ, Watkinson WP, Costa DL, Crissman KM, Richards JH, Winsett DW, Highfill JW. Ozone toxicity in the rat. III. Effect of changes in ambient temperature on pulmonary parameters. J Appl Physiol (1985) 1996; 81:1691-700. [PMID: 8904588 DOI: 10.1152/jappl.1996.81.4.1691] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023] Open
Abstract
Pulmonary toxicity of ozone (O3) was examined in adult male Fischer 344 rats exposed to 0.5 parts/million O3 for either 6 or 23 h/day over 5 days while maintained at an ambient temperature (Ta) of either 10, 22, or 34 degrees C. Toxicity was evaluated by using changes in lung volumes and the concentrations of constituents of bronchoalveolar lavage fluid that signal lung injury and/or inflammation. Results indicated that toxicity increased as Ta decreased. Exposures conducted at 10 degrees C were associated with the greatest decreases in body weight and total lung capacity and the greatest increases in lavageable protein, lysozyme, alkaline phosphatase activity, and percent neutrophils. O3 effects not modified by Ta included increases in residual volume and lavageable potassium, glucose, urea, and ascorbic acid with exposure at 34 degrees C. Most effects were attenuated during the 5 exposure days and/or returned to normal levels after 7 air recovery days, regardless of prior O3 exposure or Ta. It is possible that Ta-induced changes in metabolic rate may have altered ventilation and, therefore, the O3 doses among rats exposed at the three different Ta levels.
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Affiliation(s)
- M J Wiester
- Pulmonary Toxicology Branch, United States Environmental Protection Agency, Research Triangle Park, North Carolina 27711, USA
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Ghio AJ, Pritchard RJ, Lehmann JR, Winsett DW, Hatch GE. Lung inflammation after exposure to nonfibrous silicates increases with chelatable [Fe3+]. J Toxicol Environ Health 1996; 49:11-28. [PMID: 8816931 DOI: 10.1080/009841096160961] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/22/2023]
Abstract
Lung exposures to complexes of coordinated iron can be associated with a neutrophilic alveolitis. We tested the hypothesis that lung inflammation after intratracheal instillation of mineral oxides in rats increases with surface-complexed [Fe3+]. The 10 mineral oxides employed had measurable [Fe3+] complexed to the dust surface. The metal was incompletely coordinated, as demonstrated by the ability of the particles to catalyze electron transfer and generate thiobarbituric acid (TBA) reactive products of deoxyribose. After exclusion of those silicates containing structural iron within the crystal lattice, there was a significant correlation between the concentration of chelatable metal and TBA-reactive products (r = 0.82; p = .04). Four days after intratracheal instillation of the 10 mineral oxide particles into rats, lavage neutrophils and protein were significantly increased for all dusts compared to injected saline. Among those dusts with no structural iron, the correlation between chelatable iron concentrations and percentage neutrophils did not reach significance (r = 0.73; p = .10), but that between metal and lavage protein did (r = 0.80; p = .05). We conclude that (1) mineral oxides complex iron cations at the surface, (2) in vitro measures of oxidant generation increase with the concentration of surface iron among those dusts with no structural iron, and (3) acute inflammation following introduction of these particles into the lower respiratory tract also increases with surface iron concentrations among those mineral oxides with no structural iron.
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Affiliation(s)
- A J Ghio
- National Health and Environmental Effects Research Laboratory, Environmental Protection Agency, Research Triangle Park, North Carolina 27711, USA
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Wiester MJ, Tepper JS, Winsett DW, Crissman KM, Richards JH, Costa DL. Adaptation to ozone in rats and its association with ascorbic acid in the lung. Fundam Appl Toxicol 1996; 31:56-64. [PMID: 8998953 DOI: 10.1006/faat.1996.0075] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
Ozone (O3) adaptation is a well-known, but poorly understood phenomenon that has been demonstrated in humans and laboratory animals. This study examined pulmonary function and bronchoalveolar lavage fluid (BALF) parameters in O3-adapted F-344 rats to explore possible mechanisms of adaptation. Of particular interest was ascorbic acid (AA), an antioxidant reported to be protective against O3 injury and found to be increased in O3-adapted rats. Adaptation was induced by exposure to 0.25 ppm O3, 12 hr/day for 6 or 14 weeks and evaluated with a challenge test, one that reexposed rats to 1.0 ppm O3 and measured attenuation in the O3 effect on frequency of breathing. Pulmonary function was assessed 1 day postexposure and adaptation and BALF were evaluated 1, 3, and 7 days postexposure. Results showed that forced vital capacity increased over time but decreased due to exposure and that the 14-week, O3-exposed rats had an increase in forced expiratory flow rate. All of the O3-exposed rats that were tested demonstrated adaptation on Postexposure Days 1, 3, and 7, but it was diminished on Day 7. Adaptation was also more pronounced in rats exposed for 14 weeks. Except for AA, BALF levels of total protein, potassium, lysozyme, uric acid, and alpha-tocopherol were unaffected by O3 exposure. Lactic acid dehydrogenase, alkaline phosphatase, glucose-6-phosphate dehydrogenase, and total glutathione were also assayed but were always below detectable limits. Ascorbic acid concentrations were elevated on Days 1, 3, and 7, showing postexposure patterns similar to those found for adaptation. Significant correlation was found between AA concentration and the magnitude of adaptation (r = 0.91, p < 0.002). We conclude that AA may play an important role in mechanisms associated with O3 adaptation in rats.
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Affiliation(s)
- M J Wiester
- Pulmonary Toxicology Branch, National Health and Environmental Effects Research Laboratory, U.S. Environmental Protection Agency, Research Triangle Park, North Carolina 27711, USA
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Blazka ME, Tepper JS, Dixon D, Winsett DW, O'Connor RW, Luster MI. Pulmonary response of Fischer 344 rats to acute nose-only inhalation of indium trichloride. Environ Res 1994; 67:68-83. [PMID: 7925195 DOI: 10.1006/enrs.1994.1065] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/22/2023]
Abstract
We have previously shown that rats dosed intratracheally with indium trichloride (InCl3) develop severe lung damage and fibrosis. However, it is not clear what pulmonary effects would result following accidental occupational exposure to low concentrations of indium by inhalation. The present study uses a model of acute lung injury based on single 1-hr nose-only exposures to 0.2, 2.0, or 20 mg InCl3/m3. Exposure to 0.2 mg InCl3/m3 was capable of initiating an inflammatory response. Seven days following inhalation of 20 mg InCl3/m3 the total cell number, fibronectin, and TNF alpha levels in the bronchial alveolar lavage fluid were 8, 40, and 5 times higher than the control, respectively. Commensurate with the level of lung injury 7 days after exposure, an acute restrictive lung lesion and increased airway responsiveness to acetylcholine were observed. Forty-two days after exposure a compensatory increase in lung volume and carbon monoxide diffusing capacity in the 20 mg InCl3/m3 group suggested recovery from the lung injury. Lung collagen levels were increased in a concentration-dependent manner 42 days postexposure. These data indicate that inhalation of InCl3/m3 causes acute inflammatory changes in the lung.
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Affiliation(s)
- M E Blazka
- Environmental Immunology and Neurobiology Section, National Institute of Environmental Health Sciences, Research Triangle Park, North Carolina 27709
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Tepper JS, Costa DL, Winsett DW, Stevens MA, Doerfler DL, Watkinson WP. Near-lifetime exposure of the rat to a simulated urban profile of nitrogen dioxide: pulmonary function evaluation. Fundam Appl Toxicol 1993; 20:88-96. [PMID: 8432431 PMCID: PMC7528966 DOI: 10.1006/faat.1993.1011] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Abstract
To investigate the potential for up to a near-lifetime exposure to high-ambient levels of nitrogen dioxide (NO2) to induce functional lung damage, groups of rats were exposed to air or a simulated urban profile of NO2 (0.5 ppm background, 1.5 ppm peak) for 1, 3, 13, 52, or 78 weeks. The dynamic, static, and diffusional characteristics of the lung were evaluated postexposure in anesthetized rats. Furthermore, for the 13-, 52-, and 78-week groups, additional animals were tested after a 6-, 26-, or 17-week period in filtered air, respectively. No significant NO2 differences between exposed and control animals were found for the nitrogen washout, compliance, lung volume, or diffusion capacity of carbon monoxide measurements. At 78 weeks, however, a reduction in delta FEF25%, an estimate of convexity in the later portion of the forced expiratory flow volume curve, was observed. Breathing patterns and mechanisms were also assessed postexposure in a parallel group of similarly exposed unanesthetized rats. These rats were examined during a filtered air, 4 and 8% carbon dioxide (CO2) challenge. In the unanesthetized rat, frequency of breathing was significantly decreased and tidal volume, expiratory resistance, and inspiratory and expiratory times tended to increase. For several of these variables, the largest response also occurred at 78 weeks and seemed to be exacerbated by CO2 challenge.(ABSTRACT TRUNCATED AT 250 WORDS)
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Affiliation(s)
- J S Tepper
- ManTech Environmental, Inc., Research Triangle Park, North Carolina 27709
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Tepper JS, Costa DL, Winsett DW, Stevens MA, Doerfler DL, Watkinson WP. Near-Lifetime Exposure of the Rat to a Simulated Urban Profile of Nitrogen Dioxide: Pulmonary Function Evaluation. Toxicol Sci 1993. [PMID: 8432431 PMCID: PMC7528966 DOI: 10.1093/toxsci/20.1.88] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
To investigate the potential for up to a near-lifetime exposure to high-ambient levels of nitrogen dioxide (NO2) to induce functional lung damage, groups of rats were exposed to air or a simulated urban profile of NO2 (0.5 ppm background, 1.5 ppm peak) for 1, 3, 13, 52, or 78 weeks. The dynamic, static, and diffusional characteristics of the lung were evaluated postex-posure in anesthetized rats. Furthermore, for the 13-, 52-, and 78-week groups, additional animals were tested after a 6-, 26-, or 17-week period in filtered air, respectively. No significant NO2 differences between exposed and control animals were found for the nitrogen washout, compliance, lung volume, or diffusion capacity of carbon monoxide measurements. At 78 weeks, however, a reduction in δFEF25%, an estimate of convexity in the later portion of the forced expiratory flow volume curve, was observed. Breathing patterns and mechanics were also assessed postexposure in a parallel group of similarly exposed unanesthetized rats. These rats were examined during a filtered air, 4 and 8% carbon dioxide (CO2) challenge. In the unanesthetized rat, frequency of breathing was significantly decreased and tidal volume, expiratory resistance, and inspiratory and expiratory times tended to increase. For several of these variables, the largest response also occurred at 78 weeks and seemed to be exacerbated by CO2 challenge. For both unanesthetized and anesthetized test groups, the magnitude of the changes in pulmonary function were small and their significance was borderline, thus indicating that near-lifetime exposure to the rat of a high ambient urbanprofile of NO2 does not lead to dysfunction suggestive of degenerative lung disease.
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Affiliation(s)
- J S Tepper
- ManTech Environmental, Inc., Research Triangle Park, North Carolina 27709
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Diamond L, Kimmel EC, Lai YL, Winsett DW. Augmentation of elastase-induced emphysema by cigarette smoke. Effects of reduced nicotine content. Am Rev Respir Dis 1988; 138:1201-6. [PMID: 3202480 DOI: 10.1164/ajrccm/138.5.1201] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
To examine the role of nicotine in the augmentation of elastase-induced emphysema by cigarette smoke, animals that had been pretreated with porcine pancreatic elastase (PPE) were exposed to cigarette smokes that had a five-fold difference in their nicotine concentrations. Young adult female Long-Evans rats were divided into seven groups: (1) untreated controls; (2) low nicotine cigarette smoke exposure (Kentucky 2A1 reference cigarettes; 35.0 mg total particulate matter, 0.42 mg nicotine, and 0.38 mg nitrogen oxides per cigarette); (3) high nicotine cigarette smoke exposure (Kentucky 2R1 reference cigarettes; 38.8 mg total particulate matter, 2.2 mg nicotine, and 0.34 mg nitrogen oxides per cigarette; (4) PPE alone; (5) PPE + sham smoke exposure; (6) PPE + 2A1 smoke exposure; and (7) PPE + 2R1 smoke exposure. Three days after intratracheal administration of PPE (400 IU/kg), animals in the smoke-treated groups were exposed to 10 puffs of cigarette smoke daily, 7 days/wk for 14 wk. Sham-treated animals received room air in place of cigarette smoke. After the exposures, pulmonary function tests were performed under general anesthesia. Whole lungs were examined for gross pathologic changes, and samples of lung tissue were harvested for quantitative morphometry. Cigarette smoke exposure alone did not produce significant changes in pulmonary function or structure. On the other hand, treatment with elastase alone produced a constellation of pulmonary functional and structural changes that were pathognomonic of emphysema. Exposure to 2R1 but not 2A1 cigarette smoke significantly augmented the emphysematous changes produced by PPE.(ABSTRACT TRUNCATED AT 250 WORDS)
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Affiliation(s)
- L Diamond
- Pharmacology and Toxicology Division, University of Kentucky, College of Pharmacy, Lexington
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Kimmel EC, Winsett DW, Diamond L. Augmentation of elastase-induced emphysema by cigarette smoke. Description of a model and a review of possible mechanisms. Am Rev Respir Dis 1985; 132:885-93. [PMID: 3850732 DOI: 10.1164/arrd.1985.132.4.885] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
Rats were treated with a single endotracheal dose of purified porcine pancreatic elastase (400 IU/kg), exposed to undiluted cigarette smoke from Kentucky 2RI reference cigarettes (one 35-ml puff/min for 10 min daily, 5 days per week, for 12 wk) or with a combination of elastase followed by smoke exposure. A number of significant functional abnormalities were observed in the lungs of rats receiving elastase; these included reduced spontaneous ventilation, enlarged subdivisions of lung volume, loss of elastic recoil, and diminished gas exchange capacity. Rats receiving both elastase and cigarette smoke had significantly more severe pulmonary dysfunction than did rats treated with elastase alone. Morphometric measurements of mean linear intercept demonstrated a loss of alveolar fine structure, with enlargement of distal air spaces in elastase-treated rats. These changes were significantly more severe in rats treated with both elastase and cigarette smoke. Pulmonary function tests and morphometric measurements in sham-treated rats and in rats exposed to cigarette smoke only were not significantly different from those in untreated control animals. It is concluded that elastase-induced emphysema in rats is enhanced by exposure to whole cigarette smoke.
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