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Panneton WM, Gan Q. The Mammalian Diving Response: Inroads to Its Neural Control. Front Neurosci 2020; 14:524. [PMID: 32581683 PMCID: PMC7290049 DOI: 10.3389/fnins.2020.00524] [Citation(s) in RCA: 31] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2020] [Accepted: 04/27/2020] [Indexed: 01/03/2023] Open
Abstract
The mammalian diving response (DR) is a remarkable behavior that was first formally studied by Laurence Irving and Per Scholander in the late 1930s. The DR is called such because it is most prominent in marine mammals such as seals, whales, and dolphins, but nevertheless is found in all mammals studied. It consists generally of breathing cessation (apnea), a dramatic slowing of heart rate (bradycardia), and an increase in peripheral vasoconstriction. The DR is thought to conserve vital oxygen stores and thus maintain life by directing perfusion to the two organs most essential for life-the heart and the brain. The DR is important, not only for its dramatic power over autonomic function, but also because it alters normal homeostatic reflexes such as the baroreceptor reflex and respiratory chemoreceptor reflex. The neurons driving the reflex circuits for the DR are contained within the medulla and spinal cord since the response remains after the brainstem transection at the pontomedullary junction. Neuroanatomical and physiological data suggesting brainstem areas important for the apnea, bradycardia, and peripheral vasoconstriction induced by underwater submersion are reviewed. Defining the brainstem circuit for the DR may open broad avenues for understanding the mechanisms of suprabulbar control of autonomic function in general, as well as implicate its role in some clinical states. Knowledge of the proposed diving circuit should facilitate studies on elite human divers performing breath-holding dives as well as investigations on sudden infant death syndrome (SIDS), stroke, migraine headache, and arrhythmias. We have speculated that the DR is the most powerful autonomic reflex known.
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Affiliation(s)
- W. Michael Panneton
- Department of Pharmacological and Physiological Science, School of Medicine, Saint Louis University, St. Louis, MO, United States
| | - Qi Gan
- Department of Pharmacological and Physiological Science, School of Medicine, Saint Louis University, St. Louis, MO, United States
- Department of Pediatrics, School of Medicine, Saint Louis University, St. Louis, MO, United States
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Adetona O, Reinhardt TE, Domitrovich J, Broyles G, Adetona AM, Kleinman MT, Ottmar RD, Naeher LP. Review of the health effects of wildland fire smoke on wildland firefighters and the public. Inhal Toxicol 2016; 28:95-139. [PMID: 26915822 DOI: 10.3109/08958378.2016.1145771] [Citation(s) in RCA: 130] [Impact Index Per Article: 16.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
Each year, the general public and wildland firefighters in the US are exposed to smoke from wildland fires. As part of an effort to characterize health risks of breathing this smoke, a review of the literature was conducted using five major databases, including PubMed and MEDLINE Web of Knowledge, to identify smoke components that present the highest hazard potential, the mechanisms of toxicity, review epidemiological studies for health effects and identify the current gap in knowledge on the health impacts of wildland fire smoke exposure. Respiratory events measured in time series studies as incidences of disease-caused mortality, hospital admissions, emergency room visits and symptoms in asthma and chronic obstructive pulmonary disease patients are the health effects that are most commonly associated with community level exposure to wildland fire smoke. A few recent studies have also determined associations between acute wildland fire smoke exposure and cardiovascular health end-points. These cardiopulmonary effects were mostly observed in association with ambient air concentrations of fine particulate matter (PM2.5). However, research on the health effects of this mixture is currently limited. The health effects of acute exposures beyond susceptible populations and the effects of chronic exposures experienced by the wildland firefighter are largely unknown. Longitudinal studies of wildland firefighters during and/or after the firefighting career could help elucidate some of the unknown health impacts of cumulative exposure to wildland fire smoke, establish occupational exposure limits and help determine the types of exposure controls that may be applicable to the occupation.
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Affiliation(s)
- Olorunfemi Adetona
- a Department of Environmental Health Science , College of Public Health, University of Georgia , Athens , GA , USA .,b Division of Environmental Health Sciences , College of Public Health, the Ohio State University , Columbus , OH , USA
| | - Timothy E Reinhardt
- c AMEC Foster Wheeler Environment & Infrastructure, Inc , Seattle , WA , USA
| | - Joe Domitrovich
- d USDA Forest Service, Missoula Technology and Development Center , Missoula , MT , USA
| | - George Broyles
- e SDA Forest Service, San Dimas Technology and Development Center , San Dimas , CA , USA
| | - Anna M Adetona
- a Department of Environmental Health Science , College of Public Health, University of Georgia , Athens , GA , USA
| | - Michael T Kleinman
- f Center for Occupational and Environmental Health, University of California , Irvine , CA , USA , and
| | - Roger D Ottmar
- g USDA Forest Service, Pacific Northwest Research Station , Seattle , WA , USA
| | - Luke P Naeher
- a Department of Environmental Health Science , College of Public Health, University of Georgia , Athens , GA , USA
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Godleski JJ, Rohr AC, Kang CM, Diaz EA, Ruiz PA, Koutrakis P. Toxicological evaluation of realistic emission source aerosols (TERESA): introduction and overview. Inhal Toxicol 2011; 23 Suppl 2:1-10. [PMID: 21639692 DOI: 10.3109/08958378.2010.568019] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
Determining the health impacts of sources and components of fine particulate matter (PM(2.5)) is an important scientific goal. PM(2.5) is a complex mixture of inorganic and organic constituents that are likely to differ in their potential to cause adverse health outcomes. The Toxicological Evaluation of Realistic Emissions of Source Aerosols (TERESA) study focused on two PM sources--coal-fired power plants and mobile sources--and sought to investigate the toxicological effects of exposure to emissions from these sources. The set of papers published here document the power plant experiments. TERESA attempted to delineate health effects of primary particles, secondary (aged) particles, and mixtures of these with common atmospheric constituents. TERESA involved withdrawal of emissions from the stacks of three coal-fired power plants in the United States. The emissions were aged and atmospherically transformed in a mobile laboratory simulating downwind power plant plume processing. Toxicological evaluations were carried out in laboratory rats exposed to different emission scenarios with extensive exposure characterization. The approach employed in TERESA was ambitious and innovative. Technical challenges included the development of stack sampling technology that prevented condensation of water vapor from the power plant exhaust during sampling and transfer, while minimizing losses of primary particles; development and optimization of a photochemical chamber to provide an aged aerosol for animal exposures; development and evaluation of a denuder system to remove excess gaseous components; and development of a mobile toxicology laboratory. This paper provides an overview of the conceptual framework, design, and methods employed in the study.
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Affiliation(s)
- John J Godleski
- Department of Environmental Health, Harvard School of Public Health, Boston, MA 02115, USA.
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Seagrave J, McDonald JD, Reed MD, Seilkop SK, Mauderly JL. Responses to Subchronic Inhalation of Low Concentrations of Diesel Exhaust and Hardwood Smoke Measured in Rat Bronchoalveolar Lavage Fluid. Inhal Toxicol 2008; 17:657-70. [PMID: 16087572 DOI: 10.1080/08958370500189529] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
Abstract
Air pollution exposure is associated with adverse health effects, but the causal components and mechanisms are unclear. We compared effects of daily exposure for 6 mo to diesel exhaust (DE) or hardwood smoke (HWS) at 4 concentrations between 30 and 1000 microg/(3) of total particulate matter, or filtered air, in male and female rats. Lung lavage fluid was assayed for toxicity indicators, cytokines, and glutathione. Statistical analyses included pairwise comparisons with control and exposure-related trends, modeled using techniques that facilitated evaluation of nonlinear exposure effects. Lactate dehydrogenase increased with exposure concentration in DE-exposed females, but in other groups, low exposure concentrations caused increases while higher concentrations had less effect. Total protein in the HWS-exposed males and females followed similar patterns. Alkaline phosphatase increased in DE-exposed females, but decreased in HWS-exposed males and females. Beta-Glucuronidase decreased in HWS- and DE-exposed males, but HWS-exposed females showed decreases at low exposure concentrations and weak increases at higher exposure concentrations. Macrophage inflammatory protein-2 decreased in HWS-exposed males and females and DE-exposed females. Tumor necrosis factor-alpha levels decreased in DE-exposed females and males, but HWS-exposed males showed small increases. DE did not affect total glutathione in either gender, but HWS decreased glutathione in females, while in males, increases at low exposure concentrations but not at higher exposure levels were observed. Thus, these two combustion emissions differentially affect lung responses, with gender affecting response patterns. Furthermore, effects may be nonmonotonic functions of exposure levels, with maximal responses in environmentally or occupationally relevant exposure ranges.
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Affiliation(s)
- JeanClare Seagrave
- Lovelace Respiratory Research Institute, Albuquerque, New Mexico 87108, USA.
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Shusterman D, Tarun A, Murphy MA, Morris J. Seasonal Allergic Rhinitic and Normal Subjects Respond Differentially to Nasal Provocation with Acetic Acid Vapor. Inhal Toxicol 2008; 17:147-52. [PMID: 15788375 DOI: 10.1080/08958370590904508] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
Abstract
Individuals with seasonal allergic rhinitis (SAR) show a more marked nasal obstructive response (increases in nasal airways resistance or NAR) after provocation with chlorine gas (Cl2) than do nonrhinitic (NR) controls. We were interested in learning whether similar differential responsiveness was apparent after provocation with acetic acid vapor. Sixteen nonsmoking, nonasthmatic subjects, aged 21-63 yr, equally divided by gender and nasal allergy status, were enrolled in a single-blinded crossover study involving exposure to acetic acid (AA) vapor (15 ppm) or air for 15 min on separate days 1 wk apart. NAR was measured in triplicate before, immediately post-, and 15 min postexposure, was normalized to baseline on a given exposure day, and was expressed as Net [NAR/baseline] after acetic acid versus control (air) exposure. After log transformation to achieve normality, the mean loge of Net [NAR/baseline] was 0.22 for SAR subjects and -0.11 for NR subjects immediately postexposure (p<.05); the corresponding values were 0.24 and -0.08, respectively, at 15 min postexposure (p<.05). Inhalation of acetic acid at the (NIOSH-recommended) short-term exposure limit of 15 ppm for 15 min produces differential nasal airflow obstruction among SAR versus NR subjects, with the former showing greater physiologic reactivity to this stimulus. This differential responsiveness is consistent with our previous findings with Cl2, indicating that there may be a generalized susceptibility factor associated with allergic rhinitis. The response occurs with slight subjective nasal irritation.
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Affiliation(s)
- Dennis Shusterman
- Department of Medicine University of California, San Francisco, California, USA.
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