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Comparative Transcriptome Analysis of Organ-Specific Adaptive Responses to Hypoxia Provides Insights to Human Diseases. Genes (Basel) 2022; 13:genes13061096. [PMID: 35741857 PMCID: PMC9222487 DOI: 10.3390/genes13061096] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2022] [Revised: 06/15/2022] [Accepted: 06/17/2022] [Indexed: 02/01/2023] Open
Abstract
The common carp is a hypoxia-tolerant fish, and the understanding of its ability to live in low-oxygen environments has been applied to human health issues such as cancer and neuron degeneration. Here, we investigated differential gene expression changes during hypoxia in five common carp organs including the brain, the gill, the head kidney, the liver, and the intestine. Based on RNA sequencing, gene expression changes under hypoxic conditions were detected in over 1800 genes in common carp. The analysis of these genes further revealed that all five organs had high expression-specific properties. According to the results of the GO and KEGG, the pathways involved in the adaptation to hypoxia provided information on responses specific to each organ in low oxygen, such as glucose metabolism and energy usage, cholesterol synthesis, cell cycle, circadian rhythm, and dopamine activation. DisGeNET analysis showed that some human diseases such as cancer, diabetes, epilepsy, metabolism diseases, and social ability disorders were related to hypoxia-regulated genes. Our results suggested that common carp undergo various gene regulations in different organs under hypoxic conditions, and integrative bioinformatics may provide some potential targets for advancing disease research.
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Opinion AGR, Çakir R, De Boeck G. Better together: Cross-tolerance induced by warm acclimation and nitrate exposure improved the aerobic capacity and stress tolerance of common carp Cyprinus carpio. ECOTOXICOLOGY AND ENVIRONMENTAL SAFETY 2021; 225:112777. [PMID: 34534834 DOI: 10.1016/j.ecoenv.2021.112777] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/02/2021] [Revised: 09/08/2021] [Accepted: 09/10/2021] [Indexed: 06/13/2023]
Abstract
Climate warming is a threat of imminent concern that may exacerbate the impact of nitrate pollution on fish fitness. These stressors can individually affect the aerobic capacity and stress tolerance of fish. In combination, they may interact in unexpected ways where exposure to one stressor may heighten or reduce the resilience to another stressor and their interactive effects may not be uniform across species. Here, we examined how nitrate pollution under a warming scenario affects the aerobic scope (AS), and the hypoxia and heat stress susceptibility of a generally tolerant fish species, common carp Cyprinus carpio. We used a 3 × 2 factorial design, where fish were exposed to one of three ecologically relevant levels of nitrate (0, 50, or 200 mg NO3- L-1) and one of two temperatures (18 °C or 26 °C) for 5 weeks. Warm acclimation increased the AS by 11% due to the maintained standard metabolic rate and increased maximum metabolic rate at higher temperature, and the AS improvement seemed greater at higher nitrate concentration. Warm-acclimated fish exposed to 200 mg NO3- L-1 were less susceptible to acute hypoxia, and fish acclimated at higher temperature exhibited improved heat tolerance (critical thermal maxima, CTMax) by 5 °C. This cross-tolerance can be attributed to the hematological results including maintained haemoglobin and increased haematocrit levels that may have compensated for the initial surge in methaemoglobin at higher nitrate exposure.
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Affiliation(s)
- April Grace R Opinion
- University of Antwerp, Department of Biology, Systemic Physiological and Ecotoxicological Research (SPHERE), Groenenborgerlaan 171, 2020 Antwerp, Belgium.
| | - Rümeysa Çakir
- University of Antwerp, Department of Biology, Systemic Physiological and Ecotoxicological Research (SPHERE), Groenenborgerlaan 171, 2020 Antwerp, Belgium
| | - Gudrun De Boeck
- University of Antwerp, Department of Biology, Systemic Physiological and Ecotoxicological Research (SPHERE), Groenenborgerlaan 171, 2020 Antwerp, Belgium
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Mandic M, Bailey A, Perry SF. Hypoxia inducible factor 1-α is minimally involved in determining the time domains of the hypoxic ventilatory response in adult zebrafish (Danio rerio). Respir Physiol Neurobiol 2021; 294:103774. [PMID: 34375733 DOI: 10.1016/j.resp.2021.103774] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2021] [Revised: 04/20/2021] [Accepted: 08/05/2021] [Indexed: 01/15/2023]
Abstract
In the current study, adult zebrafish (Danio rerio) were exposed to 72 h hypoxia (90 mmHg) to assess the time domains of the hypoxia ventilatory response (HVR) and the consequence on a subsequent more severe (40 mmHg) bout of acute hypoxia. Experiments were performed on wild-type fish and mutants in which one or both paralogs of hypoxia inducible factor-1α (hif-1α) were knocked out. Although there were subtle differences among the wild-type and knockout fish, resting fV was reestablished after 2-8 h of continuous hypoxia in both groups, a striking example of hypoxic ventilatory decline (HVD). When fish were subsequently exposed to more severe hypoxia, a rapid increase in fV was observed, the magnitude of which was independent of genotype or prior exposure history. During recovery, fish that had been exposed to 72 h of 90 mmHg hypoxia exhibited a pronounced undershoot in fV, which was absent in the hif-1α double knockouts. Overall, the results revealed distinct time domains of the HVR in zebrafish that were largely Hif-1α-independent.
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Affiliation(s)
- Milica Mandic
- Department of Biology, University of Ottawa, 30 Marie Curie, Ottawa, Ontario, K1N6N5 Canada.
| | - Adrian Bailey
- Department of Biology, University of Ottawa, 30 Marie Curie, Ottawa, Ontario, K1N6N5 Canada
| | - Steve F Perry
- Department of Biology, University of Ottawa, 30 Marie Curie, Ottawa, Ontario, K1N6N5 Canada
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Stecyk JAW, Couturier CS, Abramochkin DV, Hall D, Arrant-Howell A, Kubly KL, Lockmann S, Logue K, Trueblood L, Swalling C, Pinard J, Vogt A. Cardiophysiological responses of the air-breathing Alaska blackfish to cold acclimation and chronic hypoxic submergence at 5°C. J Exp Biol 2020; 223:jeb225730. [PMID: 33020178 PMCID: PMC7687868 DOI: 10.1242/jeb.225730] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2020] [Accepted: 09/28/2020] [Indexed: 01/29/2023]
Abstract
The Alaska blackfish (Dallia pectoralis) remains active at cold temperatures when experiencing aquatic hypoxia without air access. To discern the cardiophysiological adjustments that permit this behaviour, we quantified the effect of acclimation from 15°C to 5°C in normoxia (15N and 5N fish), as well as chronic hypoxic submergence (6-8 weeks; ∼6.3-8.4 kPa; no air access) at 5°C (5H fish), on in vivo and spontaneous heart rate (fH), electrocardiogram, ventricular action potential (AP) shape and duration (APD), the background inward rectifier (IK1) and rapid delayed rectifier (IKr) K+ currents and ventricular gene expression of proteins involved in excitation-contraction coupling. In vivo fH was ∼50% slower in 5N than in 15N fish, but 5H fish did not display hypoxic bradycardia. Atypically, cold acclimation in normoxia did not induce shortening of APD or alter resting membrane potential. Rather, QT interval and APD were ∼2.6-fold longer in 5N than in 15N fish because outward IK1 and IKr were not upregulated in 5N fish. By contrast, chronic hypoxic submergence elicited a shortening of QT interval and APD, driven by an upregulation of IKr The altered electrophysiology of 5H fish was accompanied by increased gene expression of kcnh6 (3.5-fold; Kv11.2 of IKr), kcnj12 (7.4-fold; Kir2.2 of IK1) and kcnj14 (2.9-fold; Kir2.4 of IK1). 5H fish also exhibited a unique gene expression pattern that suggests modification of ventricular Ca2+ cycling. Overall, the findings reveal that Alaska blackfish exposed to chronic hypoxic submergence prioritize the continuation of cardiac performance to support an active lifestyle over reducing cardiac ATP demand.
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Affiliation(s)
- Jonathan A W Stecyk
- Department of Biological Sciences, University of Alaska Anchorage, Anchorage, AK 99508, USA
| | - Christine S Couturier
- Department of Biological Sciences, University of Alaska Anchorage, Anchorage, AK 99508, USA
| | - Denis V Abramochkin
- Department of Human and Animal Physiology, Lomonosov Moscow State University, 1-12 Leninskiye Gory, 119991 Moscow, Russia
- Ural Federal University, 19 Mira Street, 620002 Ekaterinburg, Russia
- Laboratory of Cardiac Physiology, Institute of Physiology of Kоmi Science Centre of the Ural Branch of the Russian Academy of Sciences, FRC Komi SC UB RAS, 50 Pervomayskaya Str., 167982 Syktyvkar, Komi Republic, Russia
| | - Diarmid Hall
- Department of Biological Sciences, University of Alaska Anchorage, Anchorage, AK 99508, USA
| | - Asia Arrant-Howell
- Department of Biological Sciences, University of Alaska Anchorage, Anchorage, AK 99508, USA
| | - Kerry L Kubly
- Department of Biological Sciences, University of Alaska Anchorage, Anchorage, AK 99508, USA
| | - Shyanne Lockmann
- Department of Biological Sciences, University of Alaska Anchorage, Anchorage, AK 99508, USA
| | - Kyle Logue
- Department of Biological Sciences, University of Alaska Anchorage, Anchorage, AK 99508, USA
| | - Lenett Trueblood
- Department of Biological Sciences, University of Alaska Anchorage, Anchorage, AK 99508, USA
| | - Connor Swalling
- Department of Biological Sciences, University of Alaska Anchorage, Anchorage, AK 99508, USA
| | - Jessica Pinard
- Department of Biological Sciences, University of Alaska Anchorage, Anchorage, AK 99508, USA
| | - Angela Vogt
- Department of Biological Sciences, University of Alaska Anchorage, Anchorage, AK 99508, USA
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Mu Y, Li W, Wei Z, He L, Zhang W, Chen X. Transcriptome analysis reveals molecular strategies in gills and heart of large yellow croaker (Larimichthys crocea) under hypoxia stress. FISH & SHELLFISH IMMUNOLOGY 2020; 104:304-313. [PMID: 32544557 DOI: 10.1016/j.fsi.2020.06.028] [Citation(s) in RCA: 22] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/17/2020] [Revised: 06/07/2020] [Accepted: 06/12/2020] [Indexed: 06/11/2023]
Abstract
The gills and heart are two major targets of hypoxia in fish. However, the molecular responses in fish gills and heart to hypoxia challenge remain unclear. Here, RNA-Seq technology was used to study the gene expression profiles in gills and heart of large yellow croaker (Larimichthys crocea) at 6, 24, and 48 h after hypoxia stress. A total of 1,546 and 2,746 differentially expressed genes (DEGs) were identified in gills and heart, respectively. Expression changes of nine genes in each tissue were further validated by the qPCR. Based on KEGG and Gene ontology enrichments, we found that various innate immunity-related genes, such as complement components (C1qs, C2, C3, C6, and C7), chemokines (CCL3, CCL17, CCL19, CCL25, and CXCL8_L3), chemokine receptors (CCR9, CXCR1, and CXCR3), and nitric oxide synthase (NOS), were significantly down-regulated in gills and/or heart, suggesting that innate immune processes mediated by these genes may be inhibited by hypoxia. The genes involved in both glycolysis pathway (LDHA) and tricarboxylic acid cycle (IDH2 and OGDH) were up-regulated in gills and heart of hypoxic large yellow croakers, possibly because gill and heart tissues need enough energy to accelerate gas exchange and blood circulation. Hypoxia also affected the ion transport in gills of large yellow croaker, through down-regulating the expression levels of numerous classical ion transporters, including HVCN1, SLC20A2, SLC4A4, RHBG, RHCG, and SCN4A, suggesting an energy conservation strategy to hypoxia stress. All these results indicate that the immune processes, glycolytic pathways, and ion transport were significantly altered in gills and/or heart of large yellow croaker under hypoxia, possibly contributing to maintain cellular energy balance during hypoxia. Our data, therefore, afford new information to understand the tissue-specific molecular responses of bony fish to hypoxia stress.
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Affiliation(s)
- Yinnan Mu
- Key Laboratory of Marine Biotechnology of Fujian Province, Institute of Oceanology, Fujian Agriculture and Forestry University, Fuzhou, 350002, PR China
| | - Wanru Li
- Key Laboratory of Marine Biotechnology of Fujian Province, Institute of Oceanology, Fujian Agriculture and Forestry University, Fuzhou, 350002, PR China
| | - Zuyun Wei
- Key Laboratory of Marine Biotechnology of Fujian Province, Institute of Oceanology, Fujian Agriculture and Forestry University, Fuzhou, 350002, PR China
| | - Lianghua He
- Key Laboratory of Marine Biotechnology of Fujian Province, Institute of Oceanology, Fujian Agriculture and Forestry University, Fuzhou, 350002, PR China
| | - Weini Zhang
- Key Laboratory of Marine Biotechnology of Fujian Province, Institute of Oceanology, Fujian Agriculture and Forestry University, Fuzhou, 350002, PR China
| | - Xinhua Chen
- Key Laboratory of Marine Biotechnology of Fujian Province, Institute of Oceanology, Fujian Agriculture and Forestry University, Fuzhou, 350002, PR China; Southern Marine Science and Engineering Guangdong Laboratory (Zhuhai), Zhuhai, 519000, PR China.
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Rashid I, Pathak AK, Kumar R, Srivastava P, Singh M, Murali S, Kushwaha B. Genome-Wide Comparative Analysis of HIF Binding Sites in Cyprinus Carpio for In Silico Identification of Functional Hypoxia Response Elements. Front Genet 2019; 10:659. [PMID: 31379925 PMCID: PMC6660265 DOI: 10.3389/fgene.2019.00659] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2018] [Accepted: 06/21/2019] [Indexed: 12/20/2022] Open
Abstract
Cyprinus carpio is world's most widely distributed freshwater species highly used in aquaculture. It is a hypoxia-tolerant species as it lives in oxygen-deficient environment for a long period. The tolerance potential of an animal against hypoxia relates it to induced gene expression, where a hypoxia-inducible factor (HIF) binds to a transcriptionally active site, hypoxia response element (HRE), a 5-base short motif that lies within the promoter/enhancer region of a certain gene, for inducing gene expression and preventing/minimizing hypoxia effects. HRE is functionally active when it contains another motif, the hypoxia ancillary sequence (HAS), which is typically adjacent to downstream of HRE within 7- to 15-nt space. Here, an attempt was made for mining HRE and identifying functional HIF binding sites (HBS) in a genome-wide analysis of C. carpio. For this, gene information along with the 5,000-nt upstream (-4,900 to +100) sequences of 31,466 protein coding genes was downloaded from "Gene" and "RefSeq" databases. Analysis was performed after filtration of the impracticable genes. A total of 116,148 HRE consensus sequences were mined from 29,545 genes in different promoter regions. HRE with HAS consensus motifs were found in the promoter region of 9,589 genes. Further, the already reported genes for hypoxia response in humans and zebrafish were reanalyzed for detecting HRE sites in their promoters and used for comparative analysis with gene promoters of C. carpio for providing support to identify functional HBS in the gene promoter of C. carpio. An interactive user interface HREExplorer was developed for presenting the results on the World Wide Web and visualizing possible HBS in protein coding genes in C. carpio and displaying the comparative results along with the reported hypoxia-responsive genes of zebrafish and reported hypoxia-inducible genes in humans. In this study, a set of Perl program was written for the compilation and analysis of information that might be used for a similar study in other species. This novel work may provide a workbench for analyzing the promoter regions of hypoxia-responsive genes.
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Affiliation(s)
- Iliyas Rashid
- Molecular Biology and Biotechnology Division, ICAR-National Bureau of Fish Genetic Resources, Lucknow, India.,AMITY Institute of Biotechnology, AMITY University Uttar Pradesh, Lucknow, India
| | - Ajey Kumar Pathak
- Molecular Biology and Biotechnology Division, ICAR-National Bureau of Fish Genetic Resources, Lucknow, India
| | - Ravindra Kumar
- Molecular Biology and Biotechnology Division, ICAR-National Bureau of Fish Genetic Resources, Lucknow, India
| | - Prachi Srivastava
- AMITY Institute of Biotechnology, AMITY University Uttar Pradesh, Lucknow, India
| | - Mahender Singh
- Molecular Biology and Biotechnology Division, ICAR-National Bureau of Fish Genetic Resources, Lucknow, India
| | - S Murali
- Molecular Biology and Biotechnology Division, ICAR-National Bureau of Fish Genetic Resources, Lucknow, India
| | - Basdeo Kushwaha
- Molecular Biology and Biotechnology Division, ICAR-National Bureau of Fish Genetic Resources, Lucknow, India
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Le TTY, García MR, Nachev M, Grabner D, Balsa-Canto E, Hendriks AJ, Sures B. Development of a PBPK Model for Silver Accumulation in Chub Infected with Acanthocephalan Parasites. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2018; 52:12514-12525. [PMID: 30251844 DOI: 10.1021/acs.est.8b04022] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
Simultaneous presence of metals and parasites in fish might lead to potential risks to human health. Parasites might influence metal accumulation and disturb detoxification in fish, thereby affecting biomarkers of fish responses as well as metal biomagnification in humans. It is, therefore, of importance to take into account parasite infection when investigating metal accumulation in fish. However, mechanisms of metal accumulation and distribution in fish-parasite systems are not integrated into current approaches. The present study proposes a new physiologically based pharmacokinetic model for mechanistic simulation of metal partitioning between intestinal parasites and their hosts. As a particular case, Ag accumulation in the system of chub Squalius cephalus and the acanthocephalan Pomphorhynchus tereticollis was investigated. As a novelty, fish cardiac output and organ-specific blood flow distribution were incorporated in our model. This approach distinguishes the current model from the ones developed previously. It also facilitates model extrapolation and application to varying conditions. In general, the model explained Ag accumulation in the system well, especially in chub gill, storage (including skin, muscle, and carcass), and liver. The highest concentration of Ag was found in the liver. The accumulation of Ag in the storage, liver, and gill compartments followed a similar pattern, i.e., increasing during the exposure and decreasing during the depuration. The model also generated this observed trend. However, the model had a weaker performance for simulating Ag accumulation in the intestine and the kidney. Silver accumulation in these organs was less evident with considerable variations.
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Affiliation(s)
- T T Yen Le
- Department of Aquatic Ecology and Centre for Water and Environmental Research (ZWU) , University of Duisburg-Essen , D-45141 Essen , Germany
| | - Míriam R García
- Process Engineering Group , Spanish Council for Scientific Research, IIM-CSIC , 36208 Vigo , Spain
| | - Milen Nachev
- Department of Aquatic Ecology and Centre for Water and Environmental Research (ZWU) , University of Duisburg-Essen , D-45141 Essen , Germany
| | - Daniel Grabner
- Department of Aquatic Ecology and Centre for Water and Environmental Research (ZWU) , University of Duisburg-Essen , D-45141 Essen , Germany
| | - Eva Balsa-Canto
- Process Engineering Group , Spanish Council for Scientific Research, IIM-CSIC , 36208 Vigo , Spain
| | - A Jan Hendriks
- Department of Environmental Science, Faculty of Science , Radboud University Nijmegen , 6525 HP Nijmegen , The Netherlands
| | - Bernd Sures
- Department of Aquatic Ecology and Centre for Water and Environmental Research (ZWU) , University of Duisburg-Essen , D-45141 Essen , Germany
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Zhao Z, Dong S, Xu Q. Respiratory response of grass carp Ctenopharyngodon idellus to dissolved oxygen changes at three acclimation temperatures. FISH PHYSIOLOGY AND BIOCHEMISTRY 2018; 44:63-71. [PMID: 29197037 DOI: 10.1007/s10695-017-0413-9] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/20/2016] [Accepted: 08/02/2017] [Indexed: 06/07/2023]
Abstract
Respiratory parameters of grass carp were studied during dissolved oxygen (DO) changes from normal DO to hypoxia, then return to normal DO at 15, 25, and 30 °C acclimation, respectively. The results showed that with increases of acclimation temperature at normoxia the respiratory frequency (fR), oxygen consumption rate (VO2), respiratory stroke volume (VS.R), gill ventilation (VG), and VG/VO2 of grass carp increased significantly, but the oxygen extraction efficiency (EO2) of fish decreased significantly (P < 0.05). With declines of DO levels, the fR, VS.R, VG, and VG/VO2 of fish increased significantly at different acclimation temperatures (P < 0.05). A slight increase was found in VO2, and the EO2 of fish remained almost constant above DO levels of 3.09, 2.91, and 2.54 mg l-1 at 15, 25, and 30 °C, while the VO2 and EO2 began to decrease significantly with further reductions in DO levels (P < 0.05). After 0.5 h of recovery to normoxia from hypoxia at three acclimation, the fR, VS.R, VG, and VG/VO2 of the fish decreased sharply; meanwhile, the VO2 and EO2 increased sharply (P < 0.05). The respiratory parameters of fish gradually approached initial values with prolonged recovery time to normoxia, and reached their initial values in 2.5 h at 25 and 30 °C acclimation. The critical oxygen concentrations (Cc) of fish for VO2 were 2.42 mg l-1 at 15 °C, 2.02 mg l-1 at 25 °C, and 1.84 mg l-1 at 30 °C, respectively. The results suggest that grass carp are highly adapted to varied DO and short-term hypoxia environments.
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Affiliation(s)
- Zhigang Zhao
- Heilongjiang River Fisheries Research Institute, Chinese Academy of Fishery Sciences, Harbin, 150070, People's Republic of China
| | - Shuanglin Dong
- The Key Laboratory of Mariculture, Ministry of Education, Ocean University of China, Qingdao, 266003, People's Republic of China.
| | - Qiyou Xu
- Heilongjiang River Fisheries Research Institute, Chinese Academy of Fishery Sciences, Harbin, 150070, People's Republic of China.
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Zhao ZX, Cao DC, Xu J, Xu R, Li JT, Zhang Y, Xu P, Sun XW. Diversification of the duplicated Rab1a genes in a hypoxia-tolerant fish, common carp (Cyprinus carpio). Comp Biochem Physiol B Biochem Mol Biol 2015; 188:54-62. [PMID: 26129846 DOI: 10.1016/j.cbpb.2015.06.007] [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: 01/09/2015] [Revised: 06/19/2015] [Accepted: 06/19/2015] [Indexed: 11/25/2022]
Abstract
Common carp is a widely cultivated fish with longer than 2,000 years domestication history, due to its strong environmental adaptabilities, especially hypoxia tolerance. The common carp genome has experienced a very recent whole genome duplication (WGD) event. Among a large number of highly similar duplicated genes, a pair of Ras-associated binding-GTPase 1a (Rab1a) genes were found fast diverging. Four analogous Rab1a genes were identified in the common carp genome. Comparisons of gene structures and sequences indicated Rab1a-1 and Rab1a-2 was a pair of fast diverging duplicates, while Rab1a-3 and Rab1a-4 was a pair of less diverged duplicates. All putative Rab1a proteins shared conserved GTPase domain, which enabled the proteins serve as molecular switches for vesicular trafficking. Rab1a-1 and Rab1a-2 proteins varied in their C-terminal sequences, which were generally considered to encode the membrane localization signals. Differential expression patterns were observed between Rab1a-1 and Rab1a-2 genes. In blood, muscle, spleen, and heart, the mRNA level of Rab1a-1 was higher than that of Rab1a-2. In liver and intestine, the mRNA level of Rab1a-2 was higher. Expression of Rab1a-1 and Rab1a-2 showed distinct hypoxia responses. Under severe hypoxia, Rab1a-1 expression was down-regulated in blood, while Rab1a-2 expression was up-regulated in liver. Compared with the less diverged Rab1a-3/4 gene pair, common carp Rab1a-1/2 gene pair exhibited strong characteristics of sub-functionalization, which might contribute to a sophisticated and efficient Ras-dependent regulating network for the hypoxia-tolerant fish.
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Affiliation(s)
- Zi-Xia Zhao
- CAFS Key Laboratory of Aquatic Genomics, Centre for Applied Aquatic Genomics, Chinese Academy of Fishery Sciences, Beijing 100141, China.
| | - Ding-Chen Cao
- Heilongjiang River Fisheries Research Institute, Chinese Academy of Fishery Sciences, Harbin 150070, China
| | - Jian Xu
- CAFS Key Laboratory of Aquatic Genomics, Centre for Applied Aquatic Genomics, Chinese Academy of Fishery Sciences, Beijing 100141, China
| | - Ru Xu
- CAFS Key Laboratory of Aquatic Genomics, Centre for Applied Aquatic Genomics, Chinese Academy of Fishery Sciences, Beijing 100141, China
| | - Jiong-Tang Li
- CAFS Key Laboratory of Aquatic Genomics, Centre for Applied Aquatic Genomics, Chinese Academy of Fishery Sciences, Beijing 100141, China
| | - Yan Zhang
- CAFS Key Laboratory of Aquatic Genomics, Centre for Applied Aquatic Genomics, Chinese Academy of Fishery Sciences, Beijing 100141, China
| | - Peng Xu
- CAFS Key Laboratory of Aquatic Genomics, Centre for Applied Aquatic Genomics, Chinese Academy of Fishery Sciences, Beijing 100141, China
| | - Xiao-Wen Sun
- CAFS Key Laboratory of Aquatic Genomics, Centre for Applied Aquatic Genomics, Chinese Academy of Fishery Sciences, Beijing 100141, China; Heilongjiang River Fisheries Research Institute, Chinese Academy of Fishery Sciences, Harbin 150070, China.
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Petersen L, Burleson M, Huggett D. Temperature and species-specific effects on ß3-adrenergic receptor cardiac regulation in two freshwater teleosts: Channel catfish (Ictalurus punctatus) and common carp (Cyprinus carpio). Comp Biochem Physiol A Mol Integr Physiol 2015; 185:132-41. [DOI: 10.1016/j.cbpa.2015.04.005] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/27/2014] [Revised: 04/03/2015] [Accepted: 04/05/2015] [Indexed: 11/17/2022]
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Kochová P, Cimrman R, Štengl M, Ošťádal B, Tonar Z. A mathematical model of the carp heart ventricle during the cardiac cycle. J Theor Biol 2015; 373:12-25. [PMID: 25797310 DOI: 10.1016/j.jtbi.2015.03.014] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2014] [Revised: 03/06/2015] [Accepted: 03/10/2015] [Indexed: 10/23/2022]
Abstract
The poikilothermic heart has been suggested as a model for studying some of the mechanisms of early postnatal mammalian heart adaptations. We assessed morphological parameters of the carp heart (Cyprinus carpio L.) with diastolic dimensions: heart radius (5.73mm), thickness of the compact (0.50mm) and spongy myocardium (4.34mm), in two conditions (systole, diastole): volume fraction of the compact myocardium (20.7% systole, 19.6% diastole), spongy myocardium (58.9% systole, 62.8% diastole), trabeculae (37.8% systole, 28.6% diastole), and cavities (41.5% systole, 51.9% diastole) within the ventricle; volume fraction of the trabeculae (64.1% systole, 45.5% diastole) and sinuses (35.9% systole, 54.5% diastole) within the spongy myocardium; ratio between the volume of compact and spongy myocardium (0.35 systole, 0.31 diastole); ratio between compact myocardium and trabeculae (0.55 systole, 0.69 diastole); and surface density of the trabeculae (0.095μm(-1) systole, 0.147μm(-1) diastole). We created a mathematical model of the carp heart based on actual morphometric data to simulate how the compact/spongy myocardium ratio, the permeability of the spongy myocardium, and sinus-trabeculae volume fractions within the spongy myocardium influence stroke volume, stroke work, ejection fraction and p-V diagram. Increasing permeability led to increasing and then decreasing stroke volume and work, and increasing ejection fraction. An increased amount of spongy myocardium led to an increased stroke volume, work, and ejection fraction. Varying sinus-trabeculae volume fractions within the spongy myocardium showed that an increased sinus volume fraction led to an increased stroke volume and work, and a decreased ejection fraction.
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Affiliation(s)
- Petra Kochová
- European Centre of Excellence NTIS-New Technologies for Information Society, Faculty of Applied Sciences, University of West Bohemia, Univerzitní 22, 306 14 Pilsen, Czech Republic.
| | - Robert Cimrman
- New Technologies Research Centre, University of West Bohemia, Univerzitní 8, 306 14 Pilsen, Czech Republic.
| | - Milan Štengl
- Department of Physiology and Biomedical Center, Faculty of Medicine in Pilsen, Charles University in Prague, Lidická 1, 301 66 Pilsen, Czech Republic.
| | - Bohuslav Ošťádal
- Instutite of Physiology, Academy of Sciences of the Czech Republic, Vídeňská 1083, 142 20 Prague 4, Czech Republic.
| | - Zbyněk Tonar
- European Centre of Excellence NTIS-New Technologies for Information Society, Faculty of Applied Sciences, University of West Bohemia, Univerzitní 22, 306 14 Pilsen, Czech Republic.
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15
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Abdallah SJ, Thomas BS, Jonz MG. Aquatic surface respiration and swimming behaviour in adult and developing zebrafish exposed to hypoxia. J Exp Biol 2015; 218:1777-86. [DOI: 10.1242/jeb.116343] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/05/2014] [Accepted: 04/14/2015] [Indexed: 11/20/2022]
Abstract
Severe hypoxia elicits aquatic surface respiration (ASR) behaviour in many species of fish, where ventilation of the gills at the air-water interface improves O2 uptake and survival. ASR is an important adaptation that may have given rise to air breathing in vertebrates. The neural substrate of this behaviour, however, is not defined. We characterized ASR in developing and adult zebrafish (Danio rerio) to ascertain a potential role for peripheral chemoreceptors in initiation or modulation of this response. Adult zebrafish exposed to acute, progressive hypoxia (PO2 from 158 to 15 mmHg) performed ASR with a threshold of 30 mmHg, and spent more time at the surface as PO2 decreased. Acclimation to hypoxia attenuated ASR responses. In larvae, ASR behaviour was observed between 5 and 21 days postfertilization with a threshold of 16 mmHg. Zebrafish decreased swimming behaviour (i.e. distance, velocity and acceleration) as PO2 was decreased, with a secondary increase in behaviour near or below threshold PO2. In adults that underwent a 10-day intraperitoneal injection regime of 10 µg g−1 serotonin (5-HT) or 20 µg g−1 acetylcholine (ACh), an acute bout of hypoxia (15 mmHg) increased the time engaged in ASR by 5.5 and 4.9 times, respectively, compared to controls. Larvae previously immersed in 10 µmol l−1 5-HT or ACh also displayed an increased ASR response. Our results support the notion that ASR is a behavioural response that is reliant upon input from peripheral O2 chemoreceptors. We discuss implications for the role of chemoreceptors in the evolution of air breathing.
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Affiliation(s)
- Sara J. Abdallah
- Department of Biology, University of Ottawa, Ottawa, ON, Canada, K1N 6N5
| | - Benjamin S. Thomas
- Department of Biology, University of Ottawa, Ottawa, ON, Canada, K1N 6N5
| | - Michael G. Jonz
- Department of Biology, University of Ottawa, Ottawa, ON, Canada, K1N 6N5
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16
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The beat goes on: Cardiac pacemaking in extreme conditions. Comp Biochem Physiol A Mol Integr Physiol 2014; 186:52-60. [PMID: 25178563 DOI: 10.1016/j.cbpa.2014.08.014] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2014] [Revised: 08/17/2014] [Accepted: 08/20/2014] [Indexed: 11/21/2022]
Abstract
In order for an animal to survive, the heart beat must go on in all environmental conditions, or at least restart its beat. This review is about maintaining a rhythmic heartbeat under the extreme conditions of anoxia (or very severe hypoxia) and high temperatures. It starts by considering the primitive versions of the protein channels that are responsible for initiating the heartbeat, HCN channels, divulging recent findings from the ancestral craniate, the Pacific hagfish (Eptatretus stoutii). It then explores how a heartbeat can maintain a rhythm, albeit slower, for hours without any oxygen, and sometimes without autonomic innervation. It closes with a discussion of recent work on fishes, where the cardiac rhythm can become arrhythmic when a fish experiences extreme heat.
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17
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Zhao ZX, Xu P, Cao DC, Kuang YY, Deng HX, Zhang Y, Xu LM, Li JT, Xu J, Sun XW. Duplication and differentiation of common carp (Cyprinus carpio) myoglobin genes revealed by BAC analysis. Gene 2014; 548:210-6. [DOI: 10.1016/j.gene.2014.07.034] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2013] [Revised: 05/09/2014] [Accepted: 07/11/2014] [Indexed: 12/26/2022]
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18
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Seo E, Ohishi K, Maruyama T, Imaizumi-Ohashi Y, Murakami M, Seo Y. Testing the constant-volume hypothesis by magnetic resonance imaging of Mytilus galloprovincialis heart. ACTA ACUST UNITED AC 2014; 217:964-73. [PMID: 24311801 DOI: 10.1242/jeb.092577] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
The constant-volume (CV) hypothesis was tested using the Mytilus galloprovincialis heart under two conditions. The volume of the ventricle, auricles and pericardium, and the flow in the heart and adjacent vessels were measured by magnetic resonance imaging. In synthetic seawater at 23°C (immersed condition), the end-diastolic volume (EDV), end-systolic volume (ESV) and stroke volume (SV) were 50%, 21% and 29% of the heart volume, respectively, and the auricle volume (VA) was maximized at end-systole. Assuming a constant volume of the heart, venous return to the auricles (IV) was constant, and out-flow from the pericardium to the kidney (IPK) was 2/3 of SV. During aerial exposure (emersed condition), EDV, ESV and SV decreased to 33%, 22% and 11%, respectively. VA was maximized at end-diastole and associated with the decrease of systolic IV to 1/2 of diastolic IV, while IPK remained at 80% of the immersed condition. Based on these results--in addition to two postulates of the CV hypothesis: (1) the total volume of the heart is always the same, and (2) ventricle contraction causes a decrease in pressure in the pericardium--we modified two postulates: (3) the low pericardial pressure maintains venous return from the anterior oblique vein to the auricle, and (4) the pressure difference between the auricle and the pericardium drives haemolymph filtration through the auricle walls. We also added a new postulate: (5) dilatation of the ventricle is associated with the haemolymph output to the kidney via the renopericardial canals.
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Affiliation(s)
- Eriko Seo
- Department of Marine Ecosystem Dynamics, Division of Marine Life Science, Atmosphere and Ocean Research Institute, The University of Tokyo, Kashiwa 277-8564, Japan
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19
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Nelson JA. Breaking wind to survive: fishes that breathe air with their gut. JOURNAL OF FISH BIOLOGY 2014; 84:554-576. [PMID: 24502287 DOI: 10.1111/jfb.12323] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/12/2012] [Accepted: 12/16/2013] [Indexed: 06/03/2023]
Abstract
Several taxonomically disparate groups of fishes have evolved the ability to extract oxygen from the air with elements of their gut. Despite perceived difficulties with balancing digestive and respiratory function, gut air breathing (GAB) has evolved multiple times in fishes and several GAB families are among the most successful fish families in terms of species numbers. When gut segments evolve into an air-breathing organ (ABO), there is generally a specialized region for exchange of gases where the gut wall has diminished, vascularization has increased, capillaries have penetrated into the luminal epithelium and surfactant is produced. This specialized region is generally separated from digestive portions of the gut by sphincters. GAB fishes tend to be facultative air breathers that use air breathing to supplement aquatic respiration in hypoxic waters. Some hindgut breathers may be continuous, but not obligate air breathers (obligate air breathers drown if denied access to air). Gut ABOs are generally used only for oxygen uptake; CO₂ elimination seems to occur via the gills and skin in all GAB fishes studied. Aerial ventilation in GAB fishes is driven primarily by oxygen partial pressure of the water (PO₂) and possibly also by metabolic demand. The effect of aerial ventilation on branchial ventilation and the cardiovascular system is complex and generalizations across taxa or ABO type are not currently possible. Blood from GAB fishes generally has a low blood oxygen partial pressure that half saturates haemoglobin (p50) with a very low erythrocytic nucleoside triphosphate concentration [NTP]. GAB behaviour in nature depends on the social and ecological context of the animal as well as on physiological factors.
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Affiliation(s)
- J A Nelson
- Department of Biological Sciences, Towson University, Towson, MD 21252-0001, U.S.A
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20
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Time domains of the hypoxic cardio-respiratory response in bowfin (Amia calva). Respir Physiol Neurobiol 2014; 192:118-27. [DOI: 10.1016/j.resp.2013.12.013] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2012] [Revised: 12/18/2013] [Accepted: 12/19/2013] [Indexed: 11/18/2022]
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21
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Genz J, Jyde MB, Svendsen JC, Steffensen JF, Ramløv H. Excess post-hypoxic oxygen consumption is independent from lactate accumulation in two cyprinid fishes. Comp Biochem Physiol A Mol Integr Physiol 2013; 165:54-60. [PMID: 23396307 DOI: 10.1016/j.cbpa.2013.02.002] [Citation(s) in RCA: 47] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2012] [Revised: 02/01/2013] [Accepted: 02/03/2013] [Indexed: 11/15/2022]
Abstract
Carassius carassius responds to hypoxic conditions by conversion of lactate into ethanol, which is excreted over the gills. However, a closely related species, Cyprinus carpio, does not possess the ability to produce ethanol and would be expected to accumulate lactate during hypoxic exposure. While the increase in oxygen consumption in fish required following strenuous exercise or low environmental oxygen availability has been frequently considered, the primary contributing mechanism remains unknown. This study utilized the close relationship but strongly divergent physiology between C. carpio and C. carassius to examine the possible correlation between excess post-hypoxic oxygen consumption (EPHOC) and lactate accumulation. No difference in the EPHOC:O2 deficit ratio was observed between the two species after 2.5h anoxia, with ratios of 2.0±0.6 (C. carpio) and 1.3±0.3 (C. carassius). As predicted, lactate accumulation dynamics did significantly differ between the species in both plasma and white muscle following anoxic exposure. Significant lactate accumulation was seen in both plasma and muscle in C. carpio, but there was no accumulation of lactate in white muscle tissue of C. carassius. These findings indicate that lactate accumulated as a consequence of 2.5h anoxic exposure is not a major determinant of the resulting EPHOC.
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Affiliation(s)
- J Genz
- University of Manitoba, Department of Biological Sciences, 369 Duff Roblin, 190 Dysart Road, Winnipeg, Manitoba R3T 2N2, Canada.
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22
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Capossela KM, Brill RW, Fabrizio MC, Bushnell PG. Metabolic and cardiorespiratory responses of summer flounder Paralichthys dentatus to hypoxia at two temperatures. JOURNAL OF FISH BIOLOGY 2012; 81:1043-58. [PMID: 22880736 DOI: 10.1111/j.1095-8649.2012.03380.x] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
To quantify the tolerance of summer flounder Paralichthys dentatus to episodic hypoxia, resting metabolic rate, oxygen extraction, gill ventilation and heart rate were measured during acute progressive hypoxia at the fish's acclimation temperature (22° C) and after an acute temperature increase (to 30° C). Mean ±s.e. critical oxygen levels (i.e. the oxygen levels below which fish could not maintain aerobic metabolism) increased significantly from 27 ± 2% saturation (2·0 ± 0·1 mg O(2) l(-1)) at 22° C to 39 ± 2% saturation (2·4 ± 0·1 mg O(2) l(-1)) at 30° C. Gill ventilation and oxygen extraction changed immediately with the onset of hypoxia at both temperatures. The fractional increase in gill ventilation (from normoxia to the lowest oxygen level tested) was much larger at 22° C (6·4-fold) than at 30° C (2·7-fold). In contrast, the fractional decrease in oxygen extraction (from normoxia to the lowest oxygen levels tested) was similar at 22° C (1·7-fold) and 30° C (1·5-fold), and clearly smaller than the fractional changes in gill ventilation. In contrast to the almost immediate effects of hypoxia on respiration, bradycardia was not observed until 20 and 30% oxygen saturation at 22 and 30° C, respectively. Bradycardia was, therefore, not observed until below critical oxygen levels. The critical oxygen levels at both temperatures were near or immediately below the accepted 2·3 mg O(2) l(-1) hypoxia threshold for survival, but the increase in the critical oxygen level at 30° C suggests a lower tolerance to hypoxia after an acute increase in temperature.
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Affiliation(s)
- K M Capossela
- Department of Fisheries Science, Virginia Institute of Marine Science, College of William & Mary, P. O. Box 1346, Gloucester Point, VA 23062, USA.
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23
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24
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Stecyk JAW, Larsen BC, Nilsson GE. Intrinsic contractile properties of the crucian carp (Carassius carassius) heart during anoxic and acidotic stress. Am J Physiol Regul Integr Comp Physiol 2011; 301:R1132-42. [PMID: 21795637 DOI: 10.1152/ajpregu.00372.2010] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The crucian carp (Carassius carassius) seems unique among vertebrates in its ability to maintain cardiac performance during prolonged anoxia. We investigated whether this phenomenon arises in part from a myocardium tolerant to severe acidosis or because the anoxic crucian carp heart may not experience a severe extracellular acidosis due to the fish's ability to convert lactate to ethanol. Spontaneously contracting heart preparations from cold-acclimated (6-8°C) carp were exposed (at 6.5°C) to graded or ungraded levels of acidosis under normoxic or anoxic conditions and intrinsic contractile performance was assessed. Our results clearly show that the carp heart is tolerant of acidosis as long as oxygen is available. However, heart rate and contraction kinetics of anoxic hearts were severely impaired when extracellular pH was decreased below 7.4. Nevertheless, the crucian carp heart was capable of recovering intrinsic contractile performance upon reoxygenation regardless of the severity of the anoxic + acidotic insult. Finally, we show that increased adrenergic stimulation can ameliorate, to a degree, the negative effects of severe acidosis on the intrinsic contractile properties of the anoxic crucian carp heart. Combined, these findings indicate an avoidance of severe extracellular acidosis and adrenergic stimulation are two important factors protecting the intrinsic contractile properties of the crucian carp heart during prolonged anoxia, and thus likely facilitate the ability of the anoxic crucian carp to maintain cardiac pumping.
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Affiliation(s)
- Jonathan A W Stecyk
- Physiology Programme, Dept. of Molecular Biosciences, Univ. of Oslo, PO Box 1041, N-0316, Oslo, Norway.
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25
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Roberts HE, Smith SA. Disorders of the respiratory system in pet and ornamental fish. Vet Clin North Am Exot Anim Pract 2011; 14:179-v. [PMID: 21601810 DOI: 10.1016/j.cvex.2011.03.004] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
Abstract
The respiratory organ of fish is the gill. In addition to respiration, the gills also perform functions of acid-base regulation, osmoregulation, and excretion of nitrogenous compounds. Because of their intimate association with the environment, the gills are often the primary target organ of pollutants, poor water quality, infectious disease agents, and noninfectious problems, making examination of the gills essential to the complete examination of sick individual fish and fish populations. The degree of response of the gill tissue depends on type, severity, and degree of injury and functional changes will precede morphologic changes. Antemortem tests and water quality testing can, and should, be performed on clinically affected fish whenever possible.
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Affiliation(s)
- Helen E Roberts
- Aquatic Veterinary Services of WNY, 5 Corners Animal Hospital, 2799 Southwestern Boulevard, Suite 100, Orchard Park, NY 14127, USA.
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26
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Porteus C, Hedrick MS, Hicks JW, Wang T, Milsom WK. Time domains of the hypoxic ventilatory response in ectothermic vertebrates. J Comp Physiol B 2011; 181:311-33. [PMID: 21312038 PMCID: PMC3058336 DOI: 10.1007/s00360-011-0554-6] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2010] [Revised: 01/11/2011] [Accepted: 01/19/2011] [Indexed: 01/19/2023]
Abstract
Over a decade has passed since Powell et al. (Respir Physiol 112:123-134, 1998) described and defined the time domains of the hypoxic ventilatory response (HVR) in adult mammals. These time domains, however, have yet to receive much attention in other vertebrate groups. The initial, acute HVR of fish, amphibians and reptiles serves to minimize the imbalance between oxygen supply and demand. If the hypoxia is sustained, a suite of secondary adjustments occur giving rise to a more long-term balance (acclimatization) that allows the behaviors of normal life. These secondary responses can change over time as a function of the nature of the stimulus (the pattern and intensity of the hypoxic exposure). To add to the complexity of this process, hypoxia can also lead to metabolic suppression (the hypoxic metabolic response) and the magnitude of this is also time dependent. Unlike the original review of Powell et al. (Respir Physiol 112:123-134, 1998) that only considered the HVR in adult animals, we also consider relevant developmental time points where information is available. Finally, in amphibians and reptiles with incompletely divided hearts the magnitude of the ventilatory response will be modulated by hypoxia-induced changes in intra-cardiac shunting that also improve the match between O(2) supply and demand, and these too change in a time-dependent fashion. While the current literature on this topic is reviewed here, it is noted that this area has received little attention. We attempt to redefine time domains in a more 'holistic' fashion that better accommodates research on ectotherms. If we are to distinguish between the genetic, developmental and environmental influences underlying the various ventilatory responses to hypoxia, however, we must design future experiments with time domains in mind.
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Affiliation(s)
- Cosima Porteus
- Department of Zoology, University of British Columbia, Vancouver, BC, V6T 1Z4, Canada.
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27
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Cox GK, Sandblom E, Farrell AP. Cardiac responses to anoxia in the Pacific hagfish, Eptatretus stoutii. ACTA ACUST UNITED AC 2011; 213:3692-8. [PMID: 20952617 DOI: 10.1242/jeb.046425] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
In the absence of any previous study of the cardiac status of hagfishes during prolonged anoxia and because of their propensity for oxygen-depleted environments, the present study tested the hypothesis that the Pacific hagfish Eptatretus stoutii maintains cardiac performance during prolonged anoxia. Heart rate was halved from the routine value of 10.4±1.3 beats min⁻¹ by the sixth hour of an anoxic period and then remained stable for a further 30 h. Cardiac stroke volume increased from routine (1.3±0.1 ml kg⁻¹) to partially compensate the anoxic bradycardia, such that cardiac output decreased by only 33% from the routine value of 12.3±0.9 ml min⁻¹ kg⁻¹. Cardiac power output decreased by only 25% from the routine value of 0.26±0.02 mW g⁻¹. During recovery from prolonged anoxia, cardiac output and heart rate increased to peak values within 1.5 h. Thus, the Pacific hagfish should be acknowledged as hypoxic tolerant in terms of its ability to maintain around 70% of their normoxic cardiac performance during prolonged anoxia. This is only the second fish species to be so classified.
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Affiliation(s)
- Georgina K Cox
- Department of Zoology, University of British Columbia, Vancouver, V6T 1Z4, Canada
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28
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Tzaneva V, Perry SF. The control of breathing in goldfish (Carassius auratus) experiencing thermally induced gill remodelling. J Exp Biol 2010; 213:3666-75. [DOI: 10.1242/jeb.047431] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
SUMMARY
At temperatures below 15°C the gill lamellae of goldfish (Carassius auratus) are largely covered by an interlamellar cell mass (ILCM) which decreases the functional surface area of the gill. The presence of the ILCM in goldfish acclimated to cold water conceivably could lead to a covering of the neuroepithelial cells (NECs), which are believed to be important for sensing ambient O2 and CO2 levels. In this study we tested the hypothesis that goldfish with covered lamellae (and presumably fewer NECs exposed to the water) exhibit a decreased capacity to hyperventilate in response to hypoxic stimuli. Measurements of ventilation amplitude and frequency were performed during exposure to acute hypoxia (PwO2=30 mmHg) or following injections of the O2 chemoreceptor stimulant NaCN into the buccal cavity or caudal vein of fish acclimated to 25°C (uncovered lamellae) or 7°C (covered lamellae) to stimulate predominantly the externally or internally oriented NECs, respectively. The results demonstrated no significant differences in the response to hypoxia, with each group exhibiting similar percentage increases in ventilation amplitude (90–91%) and frequency (34–43%). Similarly, with the exception of a rightward shift of the ventilation frequency dose–response in the fish acclimated to 7°C, there were no significant differences between the two groups of fish in the ED50 values. These findings suggest that goldfish with covered lamellae retain the capacity to sense external hypoxic stimuli. Using immunohistochemistry to identify serotonin-enriched NECs, it was demonstrated that the presence of the ILCM results in the NECs being redistributed towards the distal regions of the lamellae. In 25°C-acclimated fish, the NECs were distributed evenly along the length of the lamellae with 53±3% of them in the distal half, whereas in fish acclimated to 7°C, 83±5% of the NECs were confined to the distal half. Using the neuronal marker antibody ZN-12, it was demonstrated that the NECs at the distal edges of the lamellae are innervated by nerve fibres. Thus, it is hypothesised that the capacity to sense external hypoxic stimuli in goldfish acclimated to cold water is maintained despite the increasing coverage of the gill epithelial surfaces because of a redistribution of innervated NECs to the exposed distal regions of the lamellae.
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Affiliation(s)
- Velislava Tzaneva
- Department of Biology, University of Ottawa, 30 Marie Curie, Ottawa, ON K1N 6N5, Canada
| | - Steve F. Perry
- Department of Biology, University of Ottawa, 30 Marie Curie, Ottawa, ON K1N 6N5, Canada
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29
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The GI tract in air breathing. ACTA ACUST UNITED AC 2010. [DOI: 10.1016/s1546-5098(10)03010-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register]
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30
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Janssen GJA, Jerrett AR, Black SE, Forster ME. The effects of progressive hypoxia and re-oxygenation on cardiac function, white muscle perfusion and haemoglobin saturation in anaesthetised snapper (Pagrus auratus). J Comp Physiol B 2009; 180:503-10. [PMID: 20012662 DOI: 10.1007/s00360-009-0429-2] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2009] [Revised: 10/28/2009] [Accepted: 11/24/2009] [Indexed: 10/20/2022]
Abstract
The effects of progressive hypoxia and re-oxygenation on cardiac function, white muscle perfusion and haemoglobin saturation were investigated in anaesthetised snapper (Pagrus auratus). White muscle perfusion and haemoglobin saturation were recorded in real time using fibre optic methodology. A marked fall in heart rate (HR) was evoked when the water bath dissolved oxygen (DO) concentration decreased below 1.5 mg L(-1). This bradycardia deepened over the subsequent 20 min of progressive hypoxia and noticeable arrhythmias occurred, suggesting that hypoxia had direct and severe effects on the cardiac myocytes. Perfusion to the white muscle decreased below a DO concentration of 3 mg L(-1), and oxyhaemoglobin concentration decreased once the DO fell below ca. 2 mg L(-1). During re-oxygenation, heart rate and white muscle perfusion increased as the DO concentration exceeded 1.9 +/- 0.1 mg L(-1), whereas haemoglobin saturation increased once the external DO concentration reached 2.9 mg L(-1). These changes occurred in anaesthetised fish, in which sensory function must be impaired, if not abolished. As white muscle perfusion both fell and increased prior to changes in white muscle oxyhaemoglobin saturation, a local hypoxia is more likely to be the consequence than the cause of the reduced blood delivery, and changes upstream from the tail vasculature must be responsible. HR and tissue haemoglobin concentrations did increase simultaneously on re-oxygenation suggesting an increased cardiac output as the cause.
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Affiliation(s)
- G J A Janssen
- Plant and Food Research Ltd, Seafood Production, PO Box 5114, Port Nelson, Nelson, New Zealand
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31
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Perry S, Jonz M, Gilmour K. Chapter 5 Oxygen Sensing And The Hypoxic Ventilatory Response. FISH PHYSIOLOGY 2009. [DOI: 10.1016/s1546-5098(08)00005-8] [Citation(s) in RCA: 58] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
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32
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Stecyk JAW, Galli GL, Shiels HA, Farrell AP. Cardiac survival in anoxia-tolerant vertebrates: An electrophysiological perspective. Comp Biochem Physiol C Toxicol Pharmacol 2008; 148:339-54. [PMID: 18589002 DOI: 10.1016/j.cbpc.2008.05.016] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/05/2008] [Revised: 05/31/2008] [Accepted: 05/31/2008] [Indexed: 11/24/2022]
Abstract
Certain vertebrates, such as freshwater turtles of the genus Chrysemys and Trachemys and crucian carp (Carassius carassius), have anoxia-tolerant hearts that continue to function throughout prolonged periods of anoxia (up to many months) due to successful balancing of cellular ATP supply and demand. In the present review, we summarize the current and limited understanding of the cellular mechanisms underlying this cardiac anoxia tolerance. What emerges is that cold temperature substantially modifies cardiac electrophysiology to precondition the heart for winter anoxia. Intrinsic heart rate is slowed and density of sarcolemmal ion currents substantially modified to alter cardiac action potential (AP) characteristics. These changes depress cardiac activity and reduce the energetic costs associated with ion pumping. In contrast, anoxia per se results in limited changes to cardiac AP shape or ion current densities in turtle and crucian carp, suggesting that anoxic modifications of cardiac electrophysiology to reduce ATP demand are not extensive. Additionally, as knowledge of cellular physiology in non-mammalian vertebrates is still in its infancy, we briefly discuss the cellular defense mechanisms towards the acidosis that accompanies anoxia as well as mammalian cardiac models of hypoxia/ischemia tolerance. By examining if fundamental cellular mechanisms have been conserved during the evolution of anoxia tolerance we hope to have provided a framework for the design of future experiments investigating cardiac cellular mechanisms of anoxia survival.
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Affiliation(s)
- Jonathan A W Stecyk
- Physiology Programme, Department of Molecular Biosciences, University of Oslo, PO Box 1041, N-0316, Oslo, Norway.
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33
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Scott GR, Wood CM, Sloman KA, Iftikar FI, De Boeck G, Almeida-Val VMF, Val AL. Respiratory responses to progressive hypoxia in the Amazonian oscar, Astronotus ocellatus. Respir Physiol Neurobiol 2008; 162:109-16. [PMID: 18555751 DOI: 10.1016/j.resp.2008.05.001] [Citation(s) in RCA: 52] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2008] [Revised: 04/29/2008] [Accepted: 05/01/2008] [Indexed: 12/18/2022]
Abstract
This study determined the respiratory responses to progressive hypoxia in oscar, an extremely hypoxia-tolerant Amazonian cichlid. Oscar depressed oxygen consumption rates (MO2), beginning at a critical O2 tension (Pcrit) of 46Torr, to only 14% of normoxic rates at 10Torr. Total ventilation (Vw) increased up to 4-fold, entirely due to a rise in ventilatory stroke volume (no change in ventilatory frequency), and water convection requirement (Vw/MO2) increased substantially (up to 15-fold). Gill O2 extraction fell steadily, from 60% down to 40%. Although O2 transfer factor (an index of gill O2 diffusion capacity) increased transiently in moderate hypoxia, it decreased at 10Torr, which may have caused the increased expired-arterial PO2 difference. Venous PO2 was always very low (< or =7Torr). Anaerobic metabolism made a significant contribution to ATP supply, indicated by a 3-fold increase in plasma lactate that resulted in an uncompensated metabolic acidosis. Respiration of isolated gill cells was not inhibited until below 5Torr; because gill water PO2 always exceeded this value, hypoxic ion flux arrest in oscars [Wood et al., Am. J. Physiol. Reg. Integr. Comp. Physiol. 292, R2048-R2058, 2007] is probably not caused by O2 limitation in ionocytes. We conclude that metabolic depression and tolerance of anaerobic bi-products, rather than a superior capacity for O2 supply, allow oscar to thrive in extreme hypoxia in the Amazon.
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Affiliation(s)
- Graham R Scott
- Department of Zoology, University of British Columbia, Vancouver V6T 1Z4, Canada.
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Stecyk JAW, Stensløkken KO, Nilsson GE, Farrell AP. Adenosine does not save the heart of anoxia-tolerant vertebrates during prolonged oxygen deprivation. Comp Biochem Physiol A Mol Integr Physiol 2007; 147:961-73. [PMID: 17433747 DOI: 10.1016/j.cbpa.2007.03.002] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2007] [Revised: 02/28/2007] [Accepted: 03/01/2007] [Indexed: 11/24/2022]
Abstract
Despite adenosine being regarded as an important signaling molecule capable of coordinating ATP supply and demand during periods of oxygen deprivation in anoxia-intolerant mammals, the importance of adenosinergic cardiovascular control in anoxia-tolerant vertebrates is poorly understood. Here, we report on adenosinergic cardiovascular control during normoxia and prolonged (hours to days) oxygen deprivation for three vertebrate species tolerant of severe hypoxia/anoxia, the closely related common (Cyprinus carpio) and crucian (Carassius carassius) carp, and the freshwater turtle (Trachemys scripta). Using an intra-arterial injection of the non-specific adenosine receptor antagonist aminophylline while measuring cardiac output (Q), heart rate (f(H)) and arterial blood pressure, we establish that adenosinergic cardiovascular control is unimportant during prolonged anoxia in the freshwater turtle (6 h at 21 degrees C and 14 d at 5 degrees C) and the crucian carp (5 d at 8 degrees C). In contrast, adenosinergic control contributes to the down-regulation of cardiac activity exhibited by 5 degrees C-acclimated common carp during a 12.5 h severe hypoxia (<0.3 mg O2 l(-1)) exposure. Specifically, aminophylline injection resulted in significant increases in f(H) and Q, and a decrease in total peripheral resistance. These species-specific differences in adenosinergic cardiovascular control during prolonged periods of oxygen deprivation may be related to differences displayed by these three species in their anoxia tolerance and survival strategies.
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Affiliation(s)
- Jonathan A W Stecyk
- Department of Zoology, University of British Columbia, Vancouver, BC, Canada, V6T 1Z4.
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Farrell AP, Stecyk JAW. The heart as a working model to explore themes and strategies for anoxic survival in ectothermic vertebrates. Comp Biochem Physiol A Mol Integr Physiol 2007; 147:300-12. [PMID: 17337222 DOI: 10.1016/j.cbpa.2007.01.021] [Citation(s) in RCA: 48] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/03/2007] [Revised: 01/23/2007] [Accepted: 01/24/2007] [Indexed: 10/23/2022]
Abstract
Most vertebrates die within minutes when deprived of molecular oxygen (anoxia), in part because of cardiac failure, which can be traced to an inadequate matching of cardiac ATP supply to ATP demand. Cardiac power output (PO; estimated from the product of cardiac output and central arterial pressure and an indirect measure of cardiac ATP demand) is directly related to cardiac ATP supply up to some maximal level during both normoxia (ATP supply estimated from myocardial O(2) consumption) and anoxia (ATP supply estimated from lactate production rates). Thus, steady state PO provides an excellent means to examine anoxia tolerance strategies among ectothermic vertebrates by indicating a matching of cardiac glycolytic ATP supply and demand. Here, we summarize in vitro measurements of PO data from rainbow trout, freshwater turtles and hagfishes to provide a reasonable benchmark PO of 0.7 mW g(-1) for maximum glycolytic potential of ectothermic hearts at 15 degrees C, which corresponds to a glycolytic ATP turnover rate of about 70 nmol ATP g(-1) s(-1). Using this benchmark to evaluate in vivo PO data for hagfishes, carps and turtles, we identify two cardiac survival strategies, which in conjunction with creative waste management techniques to reduce waste accumulation, allow for long-term cardiac survival during anoxia in these anoxia-tolerant species. Hagfish and crucian carp exemplify a strategy of evolving such a low routine PO that routine cardiac ATP demand lies within the range of the maximum cardiac glycolytic potential. Common carp and freshwater turtles exemplify an active strategy of temporarily and substantially decreasing cardiac and whole body metabolism so that PO is below maximum cardiac glycolytic potential during chronic anoxia despite being quite close to this potential under normoxia.
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Affiliation(s)
- A P Farrell
- Faculty of Land and Food Systems, University of British Columbia, Vancouver, BC, Canada V6T 1Z4.
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Stecyk JAW, Farrell AP. Regulation of the cardiorespiratory system of common carp (Cyprinus carpio) during severe hypoxia at three seasonal acclimation temperatures. Physiol Biochem Zool 2006; 79:614-27. [PMID: 16691527 DOI: 10.1086/501064] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 10/04/2005] [Indexed: 11/03/2022]
Abstract
Little is known of the cardiorespiratory control mechanisms utilized by hypoxia-tolerant teleost fish to tolerate prolonged periods (h) of near anoxic exposure. Here, we report on the cardiorespiratory control mechanisms of the common carp Cyprinus carpio L. during normoxia and prolonged, severe hypoxic (<0.3 mg O(2) L(-1)) exposure at acclimation temperatures of 5 degrees C, 10 degrees C, and 15 degrees C. Through serial intra-arterial injections of alpha - and beta -adrenergic, cholinergic, and purinergic antagonists while measuring cardiac output (Q), heart rate (f(H)), ventral aortic blood pressure, and respiration rate, we established that autonomic cardiovascular and respiratory control was preserved during severe hypoxia at all three acclimation temperatures and contributed to downregulation of cardiorespiratory activity. Specifically, inhibitory cholinergic tone mediated up to 76% reductions in f(H) and Q during hypoxia, whereas the accompanying arterial hypotension was attenuated by an upregulation of an alpha -adrenergically mediated peripheral vasoconstriction. Despite the overall cardiac downregulation, a large, stimulatory cardiac beta -adrenergic tone was present during prolonged, severe hypoxia, possibly to protect the heart from attendant acidotic conditions. Purinergic blockade, following alpha -adrenergic and cholinergic antagonists, showed that the hypoxic ventilatory depression, which reversed the 2.3- to 7.7-fold increases in respiration rate that occurred with the onset of hypoxia, was a result of purinergic inhibition at all three acclimation temperatures. In contrast, purinergic inhibition of cardiac activity during hypoxia might be important only at 5 degrees C. Finally, given that cardiac power output was reduced 72%-87% during prolonged, severe hypoxia and that glycolysis yields approximately 94% less ATP per mole glucose than oxidative phosphorylation, it seems unlikely that the common carp sufficiently reduces its cardiac energy demand to a level to preclude activation of a partial Pasteur effect. This means that glycogen stores will be used and waste products will accumulate at faster rates, a finding that may help explain why the common carp cannot tolerate such extended periods of severe hypoxia (weeks to months) at cold acclimation temperatures as the freshwater turtle, which is able to reduce its cardiac energy demand to a level that does not require a Pasteur effect and also blunts autonomic cardiovascular control.
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Affiliation(s)
- J A W Stecyk
- Department of Zoology, University of British Columbia, Vancouver, Canada.
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Fraser J, Vieira de Mello L, Ward D, Rees HH, Williams DR, Fang Y, Brass A, Gracey AY, Cossins AR. Hypoxia-inducible myoglobin expression in nonmuscle tissues. Proc Natl Acad Sci U S A 2006; 103:2977-81. [PMID: 16469844 PMCID: PMC1413783 DOI: 10.1073/pnas.0508270103] [Citation(s) in RCA: 122] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2005] [Indexed: 11/18/2022] Open
Abstract
Myoglobin (Myg) is an oxygen-binding hemoprotein that is widely thought to be expressed exclusively in oxidative skeletal and cardiac myocytes, where it plays a key role in coping with chronic hypoxia. We now show in a hypoxia-tolerant fish model, that Myg is also expressed in a range of other tissues, including liver, gill, and brain. Moreover, expression of Myg transcript was substantially enhanced during chronic hypoxia, the fold-change induction being far greater in liver than muscle. By using 2D gel electrophoresis, we have confirmed that liver expresses a protein corresponding to the Myg-1 transcript and that it is significantly up-regulated during hypoxia. We have also discovered a second, unique Myg isoform, distinct from neuroglobin, which is expressed exclusively in the neural tissue but whose transcript expression was unaffected by environmental hypoxia. Both observations of nonmuscle expression and a brain-specific isoform are unprecedented, indicating that Myg may play a much wider role than previously understood and that Myg might function in the protection of tissues from deep hypoxia and ischemia as well as in reoxygenation and reperfusion injury.
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Affiliation(s)
- Jane Fraser
- *School of Biological Sciences, University of Liverpool, Liverpool L69 7ZB, United Kingdom
| | - Luciane Vieira de Mello
- *School of Biological Sciences, University of Liverpool, Liverpool L69 7ZB, United Kingdom
- School of Biological Sciences, University of Manchester, Manchester M13 9PL, United Kingdom; and
| | - Deborah Ward
- *School of Biological Sciences, University of Liverpool, Liverpool L69 7ZB, United Kingdom
| | - Huw H. Rees
- *School of Biological Sciences, University of Liverpool, Liverpool L69 7ZB, United Kingdom
| | - Daryl R. Williams
- *School of Biological Sciences, University of Liverpool, Liverpool L69 7ZB, United Kingdom
| | - Yongchang Fang
- Embrapa Recursos Genéticos e Biotecnologia, Brasília, Brazil 70770-900
| | - Andrew Brass
- Embrapa Recursos Genéticos e Biotecnologia, Brasília, Brazil 70770-900
| | - Andrew Y. Gracey
- *School of Biological Sciences, University of Liverpool, Liverpool L69 7ZB, United Kingdom
| | - Andrew R. Cossins
- *School of Biological Sciences, University of Liverpool, Liverpool L69 7ZB, United Kingdom
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Winmill RE, Chen AK, Hedrick MS. Development of the respiratory response to hypoxia in the isolated brainstem of the bullfrog Rana catesbeiana. ACTA ACUST UNITED AC 2005; 208:213-22. [PMID: 15634841 DOI: 10.1242/jeb.01399] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
Abstract
The aim of this study was to examine the effects of cellular hypoxia, and the contribution of anaerobic metabolism, on respiratory activity in bullfrogs at different stages of development. Respiratory-related neural activity was recorded from cranial nerve rootlets in isolated brainstem preparations from pre-metamorphic (Taylor-Kollros (T-K) stages VIII-XVI) and postmetamorphic tadpoles (T-K stages XXIV-XXV) and adults. Changes in fictive gill/lung activity in brainstems from pre-metamorphic tadpoles and lung activity in postmetamorphic tadpoles and adults were examined during superfusion with control (98% O(2)/2% CO(2)) or hypoxic (98% N(2)/2% CO(2)) artificial cerebrospinal fluid (aCSF). Iodoacetate (IAA; 100 micromol l(-1)) was used in conjunction with hypoxic aCSF to inhibit glycolysis. Gill burst frequency in pre-metamorphic brainstems did not change over a 3 h exposure to hypoxia and fictive lung burst frequency slowed significantly, but only after 3 h hypoxia. Blockade of glycolysis with IAA during hypoxia significantly reduced the time respiratory activity could be maintained in pre-metamorphic, but not in adult, brainstems. In brainstems from post-metamorphic tadpoles and adults, lung burst frequency became significantly more episodic within 5-15 min hypoxic exposure, but respiratory neural activity was subsequently abolished in every preparation. The cessation of fictive breathing was restored to control levels upon reoxygenation. Neither tadpole nor adult brainstems exhibited changes in neural bursts resembling 'gasping' that is observed in mammalian brainstems exposed to severe hypoxia. There was also a significant increase in the frequency of 'non-respiratory' bursts in hypoxic postmetamorphic and adult brainstems, but not in pre-metamorphic brainstems. These results indicate that pre-metamorphic tadpoles are capable of maintaining respiratory activity for 3 h or more during severe hypoxia and rely to a great extent upon anaerobic metabolism to maintain respiratory motor output. Upon metamorphosis, however, hypoxia results in significant changes in respiratory frequency and pattern, including increased lung burst episodes, non-ventilatory bursts and a reversible cessation of respiratory activity. Adults have little or no ability to maintain respiratory activity through glycolysis but, instead, stop respiratory activity until oxygen is available. This 'switch' in the respiratory response to hypoxia coincides morphologically with the loss of gills and obligate air-breathing in the postmetamorphic frog. We hypothesize that the cessation of respiratory activity in post-metamorphic tadpoles and adults is an adaptive, energy-saving response to low oxygen.
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Affiliation(s)
- Rachel E Winmill
- Department of Biological Sciences, California State University, Hayward, Hayward, CA 94542, USA
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Abstract
Like most vertebrates, humans die within minutes when deprived of molecular oxygen (anoxia), in part because of cardiac failure. In contrast, some freshwater turtles can survive anoxia for months at low temperatures, but to do so, they drastically suppress cardiac activity and autonomic cardiovascular control. Although Carassius carassius, the crucian carp, shares this anoxia tolerance, we show that it has a unique ability among vertebrates to retain normal cardiac performance and autonomic cardiovascular regulation for at least 5 days of anoxia. These responses point to an unusual tolerance of a vertebrate heart and autonomic nervous system to prolonged anoxia.
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Affiliation(s)
- Jonathan A W Stecyk
- Department of Biological Sciences, Simon Fraser University, 8888 University Drive, Burnaby V5A 1S6, Canada.
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Stecyk JAW, Overgaard J, Farrell AP, Wang T. α-Adrenergic regulation of systemic peripheral resistance and blood flow distribution in the turtleTrachemys scriptaduring anoxic submergence at 5°C and 21°C. J Exp Biol 2004; 207:269-83. [PMID: 14668311 DOI: 10.1242/jeb.00744] [Citation(s) in RCA: 66] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
SUMMARYAnoxic exposure in the anoxia-tolerant freshwater turtle is attended by substantial decreases in heart rate and blood flows, but systemic blood pressure (Psys) only decreases marginally due to an increase in systemic peripheral resistance (Rsys). Here,we investigate the role of the α-adrenergic system in modulating Rsys during anoxia at 5°C and 21°C in the turtle Trachemys scripta, and also describe how anoxia affects relative systemic blood flow distribution(%Q̇sys) and absolute tissue blood flows. Turtles were instrumented with an arterial cannula for measurement of Psys and ultrasonic flow probes on major systemic blood vessels for determination of systemic cardiac output(Q̇sys). α-Adrenergic tone was assessed from vascular injections of α-adrenergic agonists and antagonists (phenylephrine and phentolamine, respectively) during normoxia and following either 6 h (21°C) or 12 days (5°C) of anoxic submergence. Coloured microspheres, injected through a left atrial cannula during normoxia and anoxia, as well as after α-adrenergic stimulation and blockade during anoxia at both temperatures, were used to determine relative and absolute tissue blood flows.Anoxia was associated with an increased Rsys and functional α-adrenergic vasoactivity at both acclimation temperatures. However, while anoxia at 21°C was associated with a high systemicα-adrenergic tone, the progressive increase of Rsysat 5°C was not mediated by α-adrenergic control. A redistribution of blood flow away from ancillary vascular beds towards more vital circulations occurred with anoxia at both acclimation temperatures.%Q̇sys and absolute blood flow were reduced to the digestive and urogenital tissues (approximately 2- to 15-fold), while %Q̇sys and absolute blood flows to the heart and brain were maintained at normoxic levels. The importance of liver and muscle glycogen stores in fueling anaerobic metabolism were indicated by increases in%Q̇sys to the muscle at 21°C (1.3-fold) and liver at 5°C (1.7-fold). As well, the crucial importance of the turtle shell as a buffer reserve during anoxic submergence was indicated by 40-50% of Q̇sys being directed towards the shell during anoxia at both 5°C and 21°C. α-Adrenergic stimulation and blockade during anoxia caused few changes in%Q̇sys and absolute tissue blood flow. However, there was evidence of α-adrenergic vasoactivity contributing to blood flow regulation to the liver and shell during anoxic submergence at 5°C.
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Affiliation(s)
- J A W Stecyk
- Department of Biological Sciences, Simon Fraser University, Burnaby, British Columbia, Canada V5A 1S6
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