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Guo B, Sun Y, Wang Y, Zhang Y, Zheng Y, Xu S, Yang G, Ren W. Evolutionary genetics of pulmonary anatomical adaptations in deep-diving cetaceans. BMC Genomics 2024; 25:339. [PMID: 38575860 PMCID: PMC10993460 DOI: 10.1186/s12864-024-10263-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2023] [Accepted: 03/27/2024] [Indexed: 04/06/2024] Open
Abstract
BACKGROUND Cetaceans, having experienced prolonged adaptation to aquatic environments, have undergone evolutionary changes in their respiratory systems. This process of evolution has resulted in the emergence of distinctive phenotypic traits, notably the abundance of elastic fibers and thickened alveolar walls in their lungs, which may facilitate alveolar collapse during diving. This structure helps selective exchange of oxygen and carbon dioxide, while minimizing nitrogen exchange, thereby reducing the risk of DCS. Nevertheless, the scientific inquiry into the mechanisms through which these unique phenotypic characteristics govern the diving behavior of marine mammals, including cetaceans, remains unresolved. RESULTS This study entails an evolutionary analysis of 42 genes associated with pulmonary fibrosis across 45 mammalian species. Twenty-one genes in cetaceans exhibited accelerated evolution, featuring specific amino acid substitutions in 14 of them. Primarily linked to the development of the respiratory system and lung morphological construction, these genes play a crucial role. Moreover, among marine mammals, we identified eight genes undergoing positive selection, and the evolutionary rates of three genes significantly correlated with diving depth. Specifically, the SFTPC gene exhibited convergent amino acid substitutions. Through in vitro cellular experiments, we illustrated that convergent amino acid site mutations in SFTPC contribute positively to pulmonary fibrosis in marine mammals, and the presence of this phenotype can induce deep alveolar collapse during diving, thereby reducing the risk of DCS during diving. CONCLUSIONS The study unveils pivotal genetic signals in cetaceans and other marine mammals, arising through evolution. These genetic signals may influence lung characteristics in marine mammals and have been linked to a reduced risk of developing DCS. Moreover, the research serves as a valuable reference for delving deeper into human diving physiology.
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Affiliation(s)
- Boxiong Guo
- Jiangsu Key Laboratory for Bioaffiliationersity and Biotechnology, College of Life Sciences, Nanjing Normal University, 210023, Nanjing, China
| | - Yixuan Sun
- Jiangsu Key Laboratory for Bioaffiliationersity and Biotechnology, College of Life Sciences, Nanjing Normal University, 210023, Nanjing, China
| | - Yuehua Wang
- Jiangsu Key Laboratory for Bioaffiliationersity and Biotechnology, College of Life Sciences, Nanjing Normal University, 210023, Nanjing, China
| | - Ya Zhang
- Jiangsu Key Laboratory for Bioaffiliationersity and Biotechnology, College of Life Sciences, Nanjing Normal University, 210023, Nanjing, China
| | - Yu Zheng
- Jiangsu Key Laboratory for Bioaffiliationersity and Biotechnology, College of Life Sciences, Nanjing Normal University, 210023, Nanjing, China
| | - Shixia Xu
- Jiangsu Key Laboratory for Bioaffiliationersity and Biotechnology, College of Life Sciences, Nanjing Normal University, 210023, Nanjing, China
| | - Guang Yang
- Jiangsu Key Laboratory for Bioaffiliationersity and Biotechnology, College of Life Sciences, Nanjing Normal University, 210023, Nanjing, China
| | - Wenhua Ren
- Jiangsu Key Laboratory for Bioaffiliationersity and Biotechnology, College of Life Sciences, Nanjing Normal University, 210023, Nanjing, China.
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2
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Cole MR, Ware C, McHuron EA, Costa DP, Ponganis PJ, McDonald BI. Deep dives and high tissue density increase mean dive costs in California sea lions (Zalophus californianus). J Exp Biol 2023; 226:jeb246059. [PMID: 37345474 DOI: 10.1242/jeb.246059] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2023] [Accepted: 06/14/2023] [Indexed: 06/23/2023]
Abstract
Diving is central to the foraging strategies of many marine mammals and seabirds. Still, the effect of dive depth on foraging cost remains elusive because energy expenditure is difficult to measure at fine temporal scales in wild animals. We used depth and acceleration data from eight lactating California sea lions (Zalophus californianus) to model body density and investigate the effect of dive depth and tissue density on rates of energy expenditure. We calculated body density in 5 s intervals from the rate of gliding descent. We modeled body density across depth in each dive, revealing high tissue densities and diving lung volumes (DLVs). DLV increased with dive depth in four individuals. We used the buoyancy calculated from dive-specific body-density models and drag calculated from swim speed to estimate metabolic power and cost of transport in 5 s intervals during descents and ascents. Deeper dives required greater mean power for round-trip vertical transit, especially in individuals with higher tissue density. These trends likely follow from increased mean swim speed and buoyant hinderance that increasingly outweighs buoyant aid in deeper dives. This suggests that deep diving is either a 'high-cost, high-reward' strategy or an energetically expensive option to access prey when prey in shallow waters are limited, and that poor body condition may increase the energetic costs of deep diving. These results add to our mechanistic understanding of how foraging strategy and body condition affect energy expenditure in wild breath-hold divers.
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Affiliation(s)
- Mason R Cole
- Moss Landing Marine Laboratories, San Jose State University, 8272 Moss Landing Rd, Moss Landing, CA 95039, USA
| | - Colin Ware
- Center for Coastal and Ocean Mapping, University of New Hampshire, Durham, NH 03924, USA
| | - Elizabeth A McHuron
- Cooperative Institute for Climate, Ocean, and Ecosystem Studies, University of Washington, Seattle, WA 98105, USA
| | - Daniel P Costa
- Department of Ecology and Evolutionary Biology, University of California, Santa Cruz, CA 95064, USA
| | - Paul J Ponganis
- Scripps Institution of Oceanography, University of California San Diego, Center for Marine Biodiversity and Biomedicine, 8655 Kennel Way, La Jolla, CA 92037, USA
| | - Birgitte I McDonald
- Moss Landing Marine Laboratories, San Jose State University, 8272 Moss Landing Rd, Moss Landing, CA 95039, USA
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3
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Borque-Espinosa A, Ferrero-Fernández D, Capaccioni-Azzati R, Fahlman A. Lung function assessment in the Pacific walrus ( Odobenus rosmarus divergens) while resting on land and submerged in water. J Exp Biol 2021; 224:jeb227389. [PMID: 33188062 DOI: 10.1242/jeb.227389] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2020] [Accepted: 11/09/2020] [Indexed: 11/20/2022]
Abstract
In the present study, we examined lung function in healthy resting adult (born in 2003) Pacific walruses (Odobenus rosmarus divergens) by measuring respiratory flow ([Formula: see text]) using a custom-made pneumotachometer. Three female walruses (670-1025 kg) voluntarily participated in spirometry trials while spontaneously breathing on land (sitting and lying down in sternal recumbency) and floating in water. While sitting, two walruses performed active respiratory efforts, and one animal participated in lung compliance measurements. For spontaneous breaths, [Formula: see text] was lower when walruses were lying down (e.g. expiration: 7.1±1.2 l s-1) as compared with in water (9.9±1.4 l s-1), while tidal volume (VT, 11.5±4.6 l), breath duration (4.6±1.4 s) and respiratory frequency (7.6±2.2 breaths min-1) remained the same. The measured VT and specific dynamic lung compliance (0.32±0.07 cmH2O-1) for spontaneous breaths were higher than those estimated for similarly sized terrestrial mammals. VT increased with body mass (allometric mass-exponent=1.29) and ranged from 3% to 43% of the estimated total lung capacity (TLCest) for spontaneous breaths. When normalized for TLCest, the maximal expiratory [Formula: see text] ([Formula: see text]exp) was higher than that estimated in phocids, but lower than that reported in cetaceans and the California sea lion. [Formula: see text]exp was maintained over all lung volumes during spontaneous and active respiratory manoeuvres. We conclude that location (water or land) affects lung function in the walrus and should be considered when studying respiratory physiology in semi-aquatic marine mammals.
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Affiliation(s)
- Alicia Borque-Espinosa
- Fundación Oceanogràfic de la Comunitat Valenciana, Gran Vía Marqués del Turia 19, 46005 Valencia, Spain
- Universitat de València, Av. de Blasco Ibáñez 13, 46010 Valencia, Spain
| | | | | | - Andreas Fahlman
- Fundación Oceanogràfic de la Comunitat Valenciana, Gran Vía Marqués del Turia 19, 46005 Valencia, Spain
- Global Diving Research, Inc., Ottawa, ON, Canada, K2J 5E8
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4
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Hermann-Sorensen H, Thometz NM, Woodie K, Dennison-Gibby S, Reichmuth C. In Vivo Measurements of Lung Volumes in Ringed Seals: Insights from Biomedical Imaging. J Exp Biol 2020:jeb.235507. [PMID: 34005800 DOI: 10.1242/jeb.235507] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2020] [Accepted: 12/11/2020] [Indexed: 11/20/2022]
Abstract
Marine mammals rely on oxygen stored in blood, muscle, and lungs to support breath-hold diving and foraging at sea. Here, we used biomedical imaging to examine lung oxygen stores and other key respiratory parameters in living ringed seals (Pusa hispida). Three-dimensional models created from computed tomography (CT) images were used to quantify total lung capacity (TLC), respiratory dead space, minimum air volume, and total body volume to improve assessments of lung oxygen storage capacity, scaling relationships, and buoyant force estimates. Results suggest that lung oxygen stores determined in vivo are smaller than those derived from postmortem measurements. We also demonstrate that-while established allometric relationships hold well for most pinnipeds-these relationships consistently overestimate TLC for the smallest phocid seal. Finally, measures of total body volume reveal differences in body density and net vertical forces in the water column that influence costs associated with diving and foraging in free-ranging seals.
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Affiliation(s)
- Holly Hermann-Sorensen
- University of California Santa Cruz. Department of Ocean Sciences, 115 McAllister Way, Santa Cruz CA 95060, USA
| | - Nicole M Thometz
- University of San Francisco, Department of Biology. 2130 Fulton Street, San Francisco, CA 94117, USA
- University of California Santa Cruz. Institute of Marine Sciences, 115 McAllister Way, Santa Cruz CA 95060, USA
| | - Kathleen Woodie
- Alaska SeaLife Center, 301 Railway Ave, Seward, AK 99664, USA
| | | | - Colleen Reichmuth
- Alaska SeaLife Center, 301 Railway Ave, Seward, AK 99664, USA
- University of California Santa Cruz. Institute of Marine Sciences, 115 McAllister Way, Santa Cruz CA 95060, USA
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5
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Ponganis PJ. State of the art review: from the seaside to the bedside: insights from comparative diving physiology into respiratory, sleep and critical care. Thorax 2019; 74:512-518. [PMID: 30826734 DOI: 10.1136/thoraxjnl-2018-212136] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/22/2018] [Revised: 01/20/2019] [Accepted: 01/28/2019] [Indexed: 11/04/2022]
Abstract
Anatomical and physiological adaptations of animals to extreme environments provide insight into basic physiological principles and potential therapies for human disease. In that regard, the diving physiology of marine mammals and seabirds is especially relevant to pulmonary and cardiovascular function, and to the pathology and potential treatment of patients with hypoxaemia and/or ischaemia. This review highlights past and recent progress in the field of comparative diving physiology with emphasis on its potential relevance to human medicine.
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Affiliation(s)
- Paul J Ponganis
- Scripps Institution of Oceanography, University of California San Diego, La Jolla, CA, USA
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6
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Fahlman A, McHugh K, Allen J, Barleycorn A, Allen A, Sweeney J, Stone R, Faulkner Trainor R, Bedford G, Moore MJ, Jensen FH, Wells R. Resting Metabolic Rate and Lung Function in Wild Offshore Common Bottlenose Dolphins, Tursiops truncatus, Near Bermuda. Front Physiol 2018; 9:886. [PMID: 30065656 PMCID: PMC6056772 DOI: 10.3389/fphys.2018.00886] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2018] [Accepted: 06/19/2018] [Indexed: 11/16/2022] Open
Abstract
Diving mammals have evolved a suite of physiological adaptations to manage respiratory gases during extended breath-hold dives. To test the hypothesis that offshore bottlenose dolphins have evolved physiological adaptations to improve their ability for extended deep dives and as protection for lung barotrauma, we investigated the lung function and respiratory physiology of four wild common bottlenose dolphins (Tursiops truncatus) near the island of Bermuda. We measured blood hematocrit (Hct, %), resting metabolic rate (RMR, l O2 ⋅ min-1), tidal volume (VT, l), respiratory frequency (fR, breaths ⋅ min-1), respiratory flow (l ⋅ min-1), and dynamic lung compliance (CL, l ⋅ cmH2O-1) in air and in water, and compared measurements with published results from coastal, shallow-diving dolphins. We found that offshore dolphins had greater Hct (56 ± 2%) compared to shallow-diving bottlenose dolphins (range: 30–49%), thus resulting in a greater O2 storage capacity and longer aerobic diving duration. Contrary to our hypothesis, the specific CL (sCL, 0.30 ± 0.12 cmH2O-1) was not different between populations. Neither the mass-specific RMR (3.0 ± 1.7 ml O2 ⋅ min-1 ⋅ kg-1) nor VT (23.0 ± 3.7 ml ⋅ kg-1) were different from coastal ecotype bottlenose dolphins, both in the wild and under managed care, suggesting that deep-diving dolphins do not have metabolic or respiratory adaptations that differ from the shallow-diving ecotypes. The lack of respiratory adaptations for deep diving further support the recently developed hypothesis that gas management in cetaceans is not entirely passive but governed by alteration in the ventilation-perfusion matching, which allows for selective gas exchange to protect against diving related problems such as decompression sickness.
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Affiliation(s)
- Andreas Fahlman
- Fundación Oceanografic de la Comunidad Valenciana, Gran Vía Marques del Turia, Valencia, Spain.,Department of Life Sciences, Texas A&M University-Corpus Christi, Corpus Christi, TX, United States.,Woods Hole Oceanographic Institution, Woods Hole, MA, United States
| | - Katherine McHugh
- Chicago Zoological Society's Sarasota Dolphin Research Program, Mote Marine Laboratory, Sarasota, FL, United States
| | - Jason Allen
- Chicago Zoological Society's Sarasota Dolphin Research Program, Mote Marine Laboratory, Sarasota, FL, United States
| | - Aaron Barleycorn
- Chicago Zoological Society's Sarasota Dolphin Research Program, Mote Marine Laboratory, Sarasota, FL, United States
| | - Austin Allen
- Duke University Marine Lab, Beaufort, NC, United States
| | | | - Rae Stone
- Dolphin Quest, Waikoloa, HI, United States
| | | | - Guy Bedford
- Wildlife Consulting Service, Currumbin, QLD, Australia
| | - Michael J Moore
- Woods Hole Oceanographic Institution, Woods Hole, MA, United States
| | - Frants H Jensen
- Woods Hole Oceanographic Institution, Woods Hole, MA, United States.,Aarhus Institute of Advanced Studies, Aarhus University, Aarhus, Denmark
| | - Randall Wells
- Chicago Zoological Society's Sarasota Dolphin Research Program, Mote Marine Laboratory, Sarasota, FL, United States
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7
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Lillie MA, Vogl AW, Raverty S, Haulena M, McLellan WA, Stenson GB, Shadwick RE. Controlling thoracic pressures in cetaceans during a breath-hold dive: importance of the diaphragm. J Exp Biol 2017; 220:3464-3477. [DOI: 10.1242/jeb.162289] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2017] [Accepted: 07/17/2017] [Indexed: 11/20/2022]
Abstract
ABSTRACT
Internal pressures change throughout a cetacean's body during swimming or diving, and uneven pressures between the thoracic and abdominal compartments can affect the cardiovascular system. Pressure differentials could arise from ventral compression on each fluke downstroke or by a faster equilibration of the abdominal compartment with changing ambient ocean pressures compared with the thoracic compartment. If significant pressure differentials do develop, we would expect the morphology of the diaphragm to adapt to its in vivo loading. Here, we tested the hypothesis that significant pressure differentials develop between the thoracic and abdominal cavities in diving cetaceans by examining diaphragms from several cetacean and pinniped species. We found that: (1) regions of cetacean diaphragms possess subserosal collagen fibres that would stabilize the diaphragm against craniocaudal stretch; (2) subserosal collagen covers 5–60% of the thoracic diaphragm surface, and area correlates strongly with published values for swimming speed of each cetacean species (P<0.001); and (3) pinnipeds, which do not locomote by vertical fluking, do not possess this subserosal collagen. These results strongly suggest that this collagen is associated with loads experienced during a dive, and they support the hypothesis that diving cetaceans experience periods during which abdominal pressures significantly exceed thoracic pressures. Our results are consistent with the generation of pressure differentials by fluking and by different compartmental equilibration rates. Pressure differentials during diving would affect venous and arterial perfusion and alter transmural pressures in abdominal arteries.
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Affiliation(s)
- Margo A. Lillie
- Department of Zoology, University of British Columbia, Vancouver, BC, Canada V6T 1Z4
| | - A. Wayne Vogl
- Department of Cellular and Physiological Sciences, University of British Columbia, Vancouver, BC, Canada V6T 1Z3
| | - Stephen Raverty
- Animal Health Centre, 1767 Angus Campbell Road, Abbotsford, BC, Canada V3G 2M3
| | - Martin Haulena
- Vancouver Aquarium Marine Science Centre, PO Box 3232, Vancouver, BC, Canada V6G 3E2
| | - William A. McLellan
- Department of Biology and Marine Biology, University of North Carolina Wilmington, Wilmington, NC 28403, USA
| | | | - Robert E. Shadwick
- Department of Zoology, University of British Columbia, Vancouver, BC, Canada V6T 1Z4
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8
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Fahlman A, Moore MJ, Garcia-Parraga D. Respiratory function and mechanics in pinnipeds and cetaceans. J Exp Biol 2017; 220:1761-1773. [DOI: 10.1242/jeb.126870] [Citation(s) in RCA: 36] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
ABSTRACT
In this Review, we focus on the functional properties of the respiratory system of pinnipeds and cetaceans, and briefly summarize the underlying anatomy; in doing so, we provide an overview of what is currently known about their respiratory physiology and mechanics. While exposure to high pressure is a common challenge among breath-hold divers, there is a large variation in respiratory anatomy, function and capacity between species – how are these traits adapted to allow the animals to withstand the physiological challenges faced during dives? The ultra-deep diving feats of some marine mammals defy our current understanding of respiratory physiology and lung mechanics. These animals cope daily with lung compression, alveolar collapse, transient hyperoxia and extreme hypoxia. By improving our understanding of respiratory physiology under these conditions, we will be better able to define the physiological constraints imposed on these animals, and how these limitations may affect the survival of marine mammals in a changing environment. Many of the respiratory traits to survive exposure to an extreme environment may inspire novel treatments for a variety of respiratory problems in humans.
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Affiliation(s)
- Andreas Fahlman
- Fundación Oceanográfic de la Comunidad Valenciana, Gran Vía Marques del Turia 19, Valencia 46005, Spain
- Department of Life Sciences, Texas A&M University-Corpus Christi, 6300 Ocean Drive, Corpus Christi, TX 78412, USA
| | - Michael J. Moore
- Biology Department, Woods Hole Oceanographic Institution, Woods Hole, MA 02543, USA
| | - Daniel Garcia-Parraga
- Fundación Oceanográfic de la Comunidad Valenciana, Gran Vía Marques del Turia 19, Valencia 46005, Spain
- Oceanográfic-Avanqua, Ciudad de las Artes y las Ciencias, Valencia 46013, Spain
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9
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Fahlman A, Madigan J. Respiratory Function in Voluntary Participating Patagonia Sea Lions ( Otaria flavescens) in Sternal Recumbency. Front Physiol 2016; 7:528. [PMID: 27899896 PMCID: PMC5110536 DOI: 10.3389/fphys.2016.00528] [Citation(s) in RCA: 38] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2016] [Accepted: 10/24/2016] [Indexed: 11/15/2022] Open
Abstract
We measured esophageal pressures (n = 4), respiratory flow rates (n = 5), and expired O2 and CO2 (n = 4) in five adult Patagonia sea lions (Otaria flavescens, body mass range 94.3–286.0 kg) during voluntary breaths while laying down out of water. The data were used to estimate the dynamic specific lung compliance (sCL), the O2 consumption rate (V˙O2) and CO2 production rates (V˙CO2) during rest. Our results indicate that the resting tidal volume in Patagonia sea lions is approximately 47–73% of the estimated total lung capacity. The esophageal pressures indicated that expiration is passive during voluntary breaths. The average sCL of sea lions was 0.41 ± 0.11 cmH2O−1, which is similar to those measured in anesthetized sea lions and awake cetaceans, and significantly higher as compared to humans (0.08 cmH2O−1). The average estimated V˙O2 and V˙CO2 using breath-by-breath respirometry were 1.023 ± 0.327 L O2 min−1 (range: 0.695–1.514 L O2 min−1) and 0.777 ± 0.318 L CO2 min−1, (range: 0.510–1.235 L CO2 min−1), respectively, which is similar to previously published metabolic measurements from California and Steller sea lions using conventional flow-through respirometry. Our data provide end-tidal gas composition and offer novel data for respiratory physiology in pinnipeds, which may be important for clinical medicine and conservation efforts.
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Affiliation(s)
- Andreas Fahlman
- Fundación Oceanografic de la Comunidad ValencianaValencia, Spain; Department of Life Sciences, Texas A&M University-Corpus ChristiCorpus Christi, TX, USA
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10
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Updating a gas dynamics model using estimates for California sea lions (Zalophus californianus). Respir Physiol Neurobiol 2016; 234:1-8. [PMID: 27562522 DOI: 10.1016/j.resp.2016.08.006] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2016] [Revised: 07/24/2016] [Accepted: 08/21/2016] [Indexed: 11/22/2022]
Abstract
Theoretical models are used to predict how breath-hold diving vertebrates manage O2, CO2, and N2 while underwater. One recent gas dynamics model used available lung and tracheal compliance data from various species. As variation in respiratory compliance significantly affects alveolar compression and pulmonary shunt, the current study objective was to evaluate changes in model output when using species-specific parameters from California sea lions (Zalophus californianus). We explored the effects of lung and dead space compliance on the uptake of N2, O2, and CO2 in various tissues during a series of hypothetical dives. The updated parameters allowed for increased compliance of the lungs and an increased stiffness in the trachea. When comparing updated model output with a model using previous compliance values, there was a large decrease in N2 uptake but little change in O2 and CO2 levels. Therefore, previous models may overestimate N2 tensions and the risk of gas-related disease, such as decompression sickness (DCS), in marine mammals.
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11
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Herbert JA, Valentine MS, Saravanan N, Schneck MB, Pidaparti R, Fowler AA, Reynolds AM, Heise RL. Conservative fluid management prevents age-associated ventilator induced mortality. Exp Gerontol 2016; 81:101-9. [PMID: 27188767 DOI: 10.1016/j.exger.2016.05.005] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2015] [Revised: 05/09/2016] [Accepted: 05/13/2016] [Indexed: 11/19/2022]
Abstract
BACKGROUND Approximately 800 thousand patients require mechanical ventilation in the United States annually with an in-hospital mortality rate of over 30%. The majority of patients requiring mechanical ventilation are over the age of 65 and advanced age is known to increase the severity of ventilator-induced lung injury (VILI) and in-hospital mortality rates. However, the mechanisms which predispose aging ventilator patients to increased mortality rates are not fully understood. Ventilation with conservative fluid management decreases mortality rates in acute respiratory distress patients, but to date there has been no investigation of the effect of conservative fluid management on VILI and ventilator associated mortality rates. We hypothesized that age-associated increases in susceptibility and incidence of pulmonary edema strongly promote age-related increases in ventilator associated mortality. METHODS 2month old and 20month old male C57BL6 mice were mechanically ventilated with either high tidal volume (HVT) or low tidal volume (LVT) for up to 4h with either liberal or conservative fluid support. During ventilation, lung compliance, total lung capacity, and hysteresis curves were quantified. Following ventilation, bronchoalveolar lavage fluid was analyzed for total protein content and inflammatory cell infiltration. Wet to dry ratios were used to directly measure edema in excised lungs. Lung histology was performed to quantify alveolar barrier damage/destruction. Age matched non-ventilated mice were used as controls. RESULTS At 4h, both advanced age and HVT ventilation significantly increased markers of inflammation and injury, degraded pulmonary mechanics, and decreased survival rates. Conservative fluid support significantly diminished pulmonary edema and improved pulmonary mechanics by 1h in advanced age HVT subjects. In 4h ventilations, conservative fluid support significantly diminished pulmonary edema, improved lung mechanics, and resulted in significantly lower mortality rates in older subjects. CONCLUSION Our study demonstrates that conservative fluid alone can attenuate the age associated increase in ventilator associated mortality.
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Affiliation(s)
- Joseph A Herbert
- Department of Biomedical Engineering, Virginia Commonwealth University, 401 W Main St, PO Box 843067, Richmond, VA 23284, United States
| | - Michael S Valentine
- Department of Biomedical Engineering, Virginia Commonwealth University, 401 W Main St, PO Box 843067, Richmond, VA 23284, United States
| | - Nivi Saravanan
- Department of Biomedical Engineering, Virginia Commonwealth University, 401 W Main St, PO Box 843067, Richmond, VA 23284, United States
| | - Matthew B Schneck
- Department of Biomedical Engineering, Virginia Commonwealth University, 401 W Main St, PO Box 843067, Richmond, VA 23284, United States
| | | | - Alpha A Fowler
- Division of Pulmonary Disease and Critical Care Medicine, Department of Internal Medicine, Virginia Commonwealth University School of Medicine, United States
| | - Angela M Reynolds
- Department of Mathematics and Applies Mathematics 1015 Floyd Avenue P.O. Box 842014 Richmond, VA 23284-2014, United States
| | - Rebecca L Heise
- Department of Biomedical Engineering, Virginia Commonwealth University, 401 W Main St, PO Box 843067, Richmond, VA 23284, United States; Department of Physiology and Biophysics VCU School of Medicine 1101 East Marshall Street P.O. Box 980551 Richmond, VA 23298-0551, United States.
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12
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Fahlman A, Loring SH, Levine G, Rocho-Levine J, Austin T, Brodsky M. Lung mechanics and pulmonary function testing in cetaceans. J Exp Biol 2015; 218:2030-8. [DOI: 10.1242/jeb.119149] [Citation(s) in RCA: 44] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
ABSTRACT
We measured esophageal pressures, respiratory flow rates, and expired O2 and CO2 in six adult bottlenose dolphins (Tursiops truncatus) during voluntary breaths and maximal (chuff) respiratory efforts. The data were used to estimate the dynamic specific lung compliance (sCL), the O2 consumption rate (V̇O2) and CO2 production rates (V̇CO2) during rest. Our results indicate that bottlenose dolphins have the capacity to generate respiratory flow rates that exceed 130 l s−1 and 30 l s−1 during expiration and inspiration, respectively. The esophageal pressures indicated that expiration is passive during voluntary breaths, but active during maximal efforts, whereas inspiration is active for all breaths. The average sCL of dolphins was 0.31±0.04 cmH2O−1, which is considerably higher than that of humans (0.08 cmH2O−1) and that previously measured in a pilot whale (0.13 cmH2O−1). The average estimated V̇O2 and V̇CO2 using our breath-by-breath respirometry system ranged from 0.857 to 1.185 l O2 min−1 and 0.589 to 0.851 l CO2 min−1, respectively, which is similar to previously published metabolic measurements from the same animals using conventional flow-through respirometry. In addition, our custom-made system allows us to approximate end tidal gas composition. Our measurements provide novel data for respiratory physiology in cetaceans, which may be important for clinical medicine and conservation efforts.
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Affiliation(s)
- Andreas Fahlman
- Department of Life Science, Texas A&M University-Corpus Christi, 6300 Ocean Drive, Corpus Christi, TX 78412, USA
| | - Stephen H. Loring
- Department of Anesthesia, Critical Care and Pain Medicine, Beth Israel Deaconess Medical Center, Boston, MA 02215, USA
| | - Gregg Levine
- Dolphin Quest, Oahu, 5000 Kahala Ave, Honolulu, HI 96816, USA
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