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De Boeck G, Lardon I, Eyckmans M, Vu TN, Laukens K, Dommisse R, Wood CM. Spiny dogfish, Squalus suckleyi, shows a good tolerance for hypoxia but need long recovery times. CONSERVATION PHYSIOLOGY 2024; 12:coae054. [PMID: 39139733 PMCID: PMC11320369 DOI: 10.1093/conphys/coae054] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 05/12/2023] [Revised: 07/18/2024] [Accepted: 07/25/2024] [Indexed: 08/15/2024]
Abstract
Pacific spiny dogfish, Squalus suckleyi, move to shallow coastal waters during critical reproductive life stages and are thus at risk of encountering hypoxic events which occur more frequently in these areas. For effective conservation management, we need to fully understand the consequences of hypoxia on marine key species such as elasmobranchs. Because of their benthic life style, we hypothesized that S. suckleyi are hypoxia tolerant and able to efficiently regulate oxygen consumption, and that anaerobic metabolism is supported by a broad range of metabolites including ketones, fatty acids and amino acids. Therefore, we studied oxygen consumption rates, ventilation frequency and amplitude, blood gasses, acid-base regulation, and changes in plasma and tissue metabolites during progressive hypoxia. Our results show that critical oxygen levels (P crit) where oxyregulation is lost were indeed low (18.1% air saturation or 28.5 Torr at 13°C). However, many dogfish behaved as oxyconformers rather than oxyregulators. Arterial blood PO2 levels mostly decreased linearly with decreasing environmental PO2. Blood gases and acid-base status were dependent on open versus closed respirometry but in both set-ups ventilation frequency increased. Hypoxia below Pcrit resulted in an up-regulation of anaerobic glycolysis, as evidenced by increased lactate levels in all tissues except brain. Elasmobranchs typically rely on ketone bodies as oxidative substrates, and decreased concentrations of acetoacetate and β-hydroxybutyrate were observed in white muscle of hypoxic and/or recovering fish. Furthermore, reductions in isoleucine, glutamate, glutamine and other amino acids were observed. After 6 hours of normoxic recovery, changes persisted and only lactate returned to normal in most tissues. This emphasizes the importance of using suitable bioindicators adjusted to preferred metabolic pathways of the target species in conservation physiology. We conclude that Pacific spiny dogfish can tolerate severe transient hypoxic events, but recovery is slow and negative impacts can be expected when hypoxia persists.
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Affiliation(s)
- Gudrun De Boeck
- ECOSPHERE, Department of Biology, University of Antwerp, Groenenborgerlaaan 171, 2020 Antwerp, Belgium
- Bamfield Marine Sciences Centre, 100 Pachena Rd, Bamfield BC V0R 1B0, Canada
| | - Isabelle Lardon
- ECOSPHERE, Department of Biology, University of Antwerp, Groenenborgerlaaan 171, 2020 Antwerp, Belgium
- Bamfield Marine Sciences Centre, 100 Pachena Rd, Bamfield BC V0R 1B0, Canada
- INVE Aquaculture, Hoogveld 93, 9200 Dendermonde, Belgium
| | - Marleen Eyckmans
- ECOSPHERE, Department of Biology, University of Antwerp, Groenenborgerlaaan 171, 2020 Antwerp, Belgium
- Bamfield Marine Sciences Centre, 100 Pachena Rd, Bamfield BC V0R 1B0, Canada
- Pharmaceutical, Biomedical and Veterinary Sciences, Universiteitsplein 1, 2610 Wilrijk, Belgium
| | - Trung Nghia Vu
- Adrem Data Lab, Department of Computer Science, University of Antwerp, Middelheimlaan 1, 2020 Antwerp, Belgium
- Department of Medical Epidemiology and Biostatistics, Karolinska Institutet, Nobels väg 12A, 171 65 Solna, Sweden
| | - Kris Laukens
- Adrem Data Lab, Department of Computer Science, University of Antwerp, Middelheimlaan 1, 2020 Antwerp, Belgium
| | - Roger Dommisse
- Department of Chemistry, University of Antwerp, Groenenborgerlaan 171, 2020 Antwerpen, Belgium
| | - Chris M Wood
- Bamfield Marine Sciences Centre, 100 Pachena Rd, Bamfield BC V0R 1B0, Canada
- Department of Zoology, University of British Columbia, 6270 University Blvd, Vancouver, BC, V6T 1Z4, Canada
- Department of Biology, McMaster University, 1280 Main St. West, Hamilton, ON, L8S 4K1, Canada
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Perry SF, Pan YK, Gilmour KM. Insights into the control and consequences of breathing adjustments in fishes-from larvae to adults. Front Physiol 2023; 14:1065573. [PMID: 36793421 PMCID: PMC9923008 DOI: 10.3389/fphys.2023.1065573] [Citation(s) in RCA: 9] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2022] [Accepted: 01/11/2023] [Indexed: 01/31/2023] Open
Abstract
Adjustments of ventilation in fishes to regulate the volume of water flowing over the gills are critically important responses to match branchial gas transfer with metabolic needs and to defend homeostasis during environmental fluctuations in O2 and/or CO2 levels. In this focused review, we discuss the control and consequences of ventilatory adjustments in fish, briefly summarizing ventilatory responses to hypoxia and hypercapnia before describing the current state of knowledge of the chemoreceptor cells and molecular mechanisms involved in sensing O2 and CO2. We emphasize, where possible, insights gained from studies on early developmental stages. In particular, zebrafish (Danio rerio) larvae have emerged as an important model for investigating the molecular mechanisms of O2 and CO2 chemosensing as well as the central integration of chemosensory information. Their value stems, in part, from their amenability to genetic manipulation, which enables the creation of loss-of-function mutants, optogenetic manipulation, and the production of transgenic fish with specific genes linked to fluorescent reporters or biosensors.
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Montgomery DW, Kwan GT, Davison WG, Finlay J, Berry A, Simpson SD, Engelhard GH, Birchenough SNR, Tresguerres M, Wilson RW. Rapid blood acid-base regulation by European sea bass (Dicentrarchus labrax) in response to sudden exposure to high environmental CO2. J Exp Biol 2022; 225:jeb242735. [PMID: 35005768 PMCID: PMC8917447 DOI: 10.1242/jeb.242735] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2021] [Accepted: 12/20/2021] [Indexed: 11/22/2022]
Abstract
Fish in coastal ecosystems can be exposed to acute variations in CO2 of between 0.2 and 1 kPa CO2 (2000-10,000 µatm). Coping with this environmental challenge will depend on the ability to rapidly compensate for the internal acid-base disturbance caused by sudden exposure to high environmental CO2 (blood and tissue acidosis); however, studies about the speed of acid-base regulatory responses in marine fish are scarce. We observed that upon sudden exposure to ∼1 kPa CO2, European sea bass (Dicentrarchus labrax) completely regulate erythrocyte intracellular pH within ∼40 min, thus restoring haemoglobin-O2 affinity to pre-exposure levels. Moreover, blood pH returned to normal levels within ∼2 h, which is one of the fastest acid-base recoveries documented in any fish. This was achieved via a large upregulation of net acid excretion and accumulation of HCO3- in blood, which increased from ∼4 to ∼22 mmol l-1. While the abundance and intracellular localisation of gill Na+/K+-ATPase (NKA) and Na+/H+ exchanger 3 (NHE3) remained unchanged, the apical surface area of acid-excreting gill ionocytes doubled. This constitutes a novel mechanism for rapidly increasing acid excretion during sudden blood acidosis. Rapid acid-base regulation was completely prevented when the same high CO2 exposure occurred in seawater with experimentally reduced HCO3- and pH, probably because reduced environmental pH inhibited gill H+ excretion via NHE3. The rapid and robust acid-base regulatory responses identified will enable European sea bass to maintain physiological performance during large and sudden CO2 fluctuations that naturally occur in coastal environments.
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Affiliation(s)
| | - Garfield T. Kwan
- Marine Biology Research Division, Scripps Institution of Oceanography, University of California San Diego, 9500 Gilman Drive, La Jolla, CA 92093, USA
- National Oceanic and Atmospheric Administration Fisheries Service, Southwest Fisheries Science Center, 8901 La Jolla Shores Drive, La Jolla, CA 92037, USA
| | - William G. Davison
- Biosciences, Geoffrey Pope Building, University of Exeter, Exeter, EX4 4QD, UK
| | - Jennifer Finlay
- Biosciences, Geoffrey Pope Building, University of Exeter, Exeter, EX4 4QD, UK
| | - Alex Berry
- Biosciences, Geoffrey Pope Building, University of Exeter, Exeter, EX4 4QD, UK
| | - Stephen D. Simpson
- Biosciences, Geoffrey Pope Building, University of Exeter, Exeter, EX4 4QD, UK
| | - Georg H. Engelhard
- Centre for Environment, Fisheries & Aquaculture Science (Cefas), Pakefield Road, Lowestoft, NR330HT, UK
- School of Environmental Sciences, University of East Anglia, Norwich, NR4 7TJ, UK
| | - Silvana N. R. Birchenough
- Centre for Environment, Fisheries & Aquaculture Science (Cefas), Pakefield Road, Lowestoft, NR330HT, UK
| | - Martin Tresguerres
- Marine Biology Research Division, Scripps Institution of Oceanography, University of California San Diego, 9500 Gilman Drive, La Jolla, CA 92093, USA
| | - Rod W. Wilson
- Biosciences, Geoffrey Pope Building, University of Exeter, Exeter, EX4 4QD, UK
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Schwieterman GD, Crear DP, Anderson BN, Lavoie DR, Sulikowski JA, Bushnell PG, Brill RW. Combined Effects of Acute Temperature Change and Elevated pCO 2 on the Metabolic Rates and Hypoxia Tolerances of Clearnose Skate ( Rostaraja eglanteria), Summer Flounder ( Paralichthys dentatus), and Thorny Skate ( Amblyraja radiata). BIOLOGY 2019; 8:biology8030056. [PMID: 31357558 PMCID: PMC6783964 DOI: 10.3390/biology8030056] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 05/31/2019] [Revised: 07/14/2019] [Accepted: 07/18/2019] [Indexed: 01/02/2023]
Abstract
Understanding how rising temperatures, ocean acidification, and hypoxia affect the performance of coastal fishes is essential to predicting species-specific responses to climate change. Although a population's habitat influences physiological performance, little work has explicitly examined the multi-stressor responses of species from habitats differing in natural variability. Here, clearnose skate (Rostaraja eglanteria) and summer flounder (Paralichthys dentatus) from mid-Atlantic estuaries, and thorny skate (Amblyraja radiata) from the Gulf of Maine, were acutely exposed to current and projected temperatures (20, 24, or 28 °C; 22 or 30 °C; and 9, 13, or 15 °C, respectively) and acidification conditions (pH 7.8 or 7.4). We tested metabolic rates and hypoxia tolerance using intermittent-flow respirometry. All three species exhibited increases in standard metabolic rate under an 8 °C temperature increase (Q10 of 1.71, 1.07, and 2.56, respectively), although this was most pronounced in the thorny skate. At the lowest test temperature and under the low pH treatment, all three species exhibited significant increases in standard metabolic rate (44-105%; p < 0.05) and decreases in hypoxia tolerance (60-84% increases in critical oxygen pressure; p < 0.05). This study demonstrates the interactive effects of increasing temperature and changing ocean carbonate chemistry are species-specific, the implications of which should be considered within the context of habitat.
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Affiliation(s)
- Gail D Schwieterman
- Virginia Institute of Marine Science, College of William and Mary, Gloucester Point, VA 23062, USA.
| | - Daniel P Crear
- Virginia Institute of Marine Science, College of William and Mary, Gloucester Point, VA 23062, USA
| | - Brooke N Anderson
- Marine Sciences Department, University of New England, Biddeford, ME 04005, USA
| | - Danielle R Lavoie
- Department of Biology, Marine Biology, and Environmental Science, Roger Williams University, Bristol, RI 02809, USA
| | - James A Sulikowski
- School of Mathematical & Natural Sciences, Arizona State University, Glendale, AZ 85306, USA
| | - Peter G Bushnell
- Department of Biological Sciences, Indiana University South Bend, South Bend, IN, 46615, USA
| | - Richard W Brill
- Virginia Institute of Marine Science, College of William and Mary, Gloucester Point, VA 23062, USA
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5
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Florindo LH, Armelin VA, McKenzie DJ, Rantin FT. Control of air-breathing in fishes: Central and peripheral receptors. Acta Histochem 2018; 120:642-653. [PMID: 30219242 DOI: 10.1016/j.acthis.2018.08.010] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
Abstract
This review considers the environmental and systemic factors that can stimulate air-breathing responses in fishes with bimodal respiration, and how these may be controlled by peripheral and central chemoreceptors. The systemic factors that stimulate air-breathing in fishes are usually related to conditions that increase the O2 demand of these animals (e.g. physical exercise, digestion and increased temperature), while the environmental factors are usually related to conditions that impair their capacity to meet this demand (e.g. aquatic/aerial hypoxia, aquatic/aerial hypercarbia, reduced aquatic hidrogenionic potential and environmental pollution). It is now well-established that peripheral chemoreceptors, innervated by cranial nerves, drive increased air-breathing in response to environmental hypoxia and/or hypercarbia. These receptors are, in general, sensitive to O2 and/or CO2/H+ levels in the blood and/or the environment. Increased air-breathing in response to elevated O2 demand may also be driven by the peripheral chemoreceptors that monitor O2 levels in the blood. Very little is known about central chemoreception in air-breathing fishes, the data suggest that central chemosensitivity to CO2/H+ is more prominent in sarcopterygians than in actinopterygians. A great deal remains to be understood about control of air-breathing in fishes, in particular to what extent control systems may show commonalities (or not) among species or groups that have evolved air-breathing independently, and how information from the multiple peripheral (and possibly central) chemoreceptors is integrated to control the balance of aerial and aquatic respiration in these animals.
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Affiliation(s)
- Luiz Henrique Florindo
- Department of Zoology and Botany, São Paulo State University (UNESP), Rua Cristóvão Colombo, 2265, São José do Rio Preto, SP, 15054-000, Brazil; Aquaculture Center (CAUNESP), São Paulo State University (UNESP), Rodovia Prof. Paulo Donato Castellane, n/n, Jaboticabal, SP, 14884-900, Brazil
| | - Vinicius Araújo Armelin
- Department of Zoology and Botany, São Paulo State University (UNESP), Rua Cristóvão Colombo, 2265, São José do Rio Preto, SP, 15054-000, Brazil
| | - David John McKenzie
- Centre for Marine Biodiversity Exploitation and Conservation, UMR9190 (IRD, Ifremer, UM, CNRS), Université Montpellier, Place Eugène Bataillon cc 093, 34095 Montpellier Cedex 5, France; Department of Physiological Sciences, Federal University of São Carlos (UFSCar), Rodovia Washington Luiz, km 235, São Carlos, SP, 13565-905, Brazil
| | - Francisco Tadeu Rantin
- Department of Physiological Sciences, Federal University of São Carlos (UFSCar), Rodovia Washington Luiz, km 235, São Carlos, SP, 13565-905, Brazil.
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6
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Ventilatory responses of the clown knifefish, Chitala ornata, to hypercarbia and hypercapnia. J Comp Physiol B 2018; 188:581-589. [DOI: 10.1007/s00360-018-1150-9] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2017] [Revised: 02/13/2018] [Accepted: 02/17/2018] [Indexed: 12/31/2022]
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7
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Davis BE, Miller NA, Flynn EE, Todgham AE. Juvenile Antarctic rockcod (Trematomus bernacchii) are physiologically robust to CO2-acidified seawater. ACTA ACUST UNITED AC 2016; 219:1203-13. [PMID: 26944503 DOI: 10.1242/jeb.133173] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2015] [Accepted: 02/15/2016] [Indexed: 01/04/2023]
Abstract
To date, numerous studies have shown negative impacts of CO2-acidified seawater (i.e. ocean acidification, OA) on marine organisms, including calcifying invertebrates and fishes; however, limited research has been conducted on the physiological effects of OA on polar fishes and even less on the impact of OA on early developmental stages of polar fishes. We evaluated aspects of aerobic metabolism and cardiorespiratory physiology of juvenile emerald rockcod, ITALIC! Trematomus bernacchii, an abundant fish in the Ross Sea, Antarctica, to elevated partial pressure of carbon dioxide ( ITALIC! PCO2 ) [420 (ambient), 650 (moderate) and 1050 (high) μatm ITALIC! PCO2 ] over a 1 month period. We examined cardiorespiratory physiology, including heart rate, stroke volume, cardiac output and ventilation rate, whole organism metabolism via oxygen consumption rate and sub-organismal aerobic capacity by citrate synthase enzyme activity. Juvenile fish showed an increase in ventilation rate under high ITALIC! PCO2 compared with ambient ITALIC! PCO2 , whereas cardiac performance, oxygen consumption and citrate synthase activity were not significantly affected by elevated ITALIC! PCO2 Acclimation time had a significant effect on ventilation rate, stroke volume, cardiac output and citrate synthase activity, such that all metrics increased over the 4 week exposure period. These results suggest that juvenile emerald rockcod are robust to near-future increases in OA and may have the capacity to adjust for future increases in ITALIC! PCO2 by increasing acid-base compensation through increased ventilation.
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Affiliation(s)
- Brittany E Davis
- Department of Animal Sciences, University of California Davis, Davis, CA 95616, USA Department of Wildlife, Fish and Conservation Biology, University of California Davis, Davis, CA 95616, USA
| | - Nathan A Miller
- Department of Animal Sciences, University of California Davis, Davis, CA 95616, USA Romberg Tiburon Center for Environmental Studies, San Francisco State University, Tiburon, CA 94920, USA
| | - Erin E Flynn
- Department of Animal Sciences, University of California Davis, Davis, CA 95616, USA
| | - Anne E Todgham
- Department of Animal Sciences, University of California Davis, Davis, CA 95616, USA
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8
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Ern R, Esbaugh AJ. Hyperventilation and blood acid–base balance in hypercapnia exposed red drum (Sciaenops ocellatus). J Comp Physiol B 2016; 186:447-60. [DOI: 10.1007/s00360-016-0971-7] [Citation(s) in RCA: 33] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2015] [Revised: 02/02/2016] [Accepted: 02/12/2016] [Indexed: 01/07/2023]
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De Boeck G, Wood CM. Does ammonia trigger hyperventilation in the elasmobranch, Squalus acanthias suckleyi? Respir Physiol Neurobiol 2014; 206:25-35. [PMID: 25462837 DOI: 10.1016/j.resp.2014.11.009] [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] [Received: 07/13/2014] [Revised: 11/12/2014] [Accepted: 11/13/2014] [Indexed: 11/26/2022]
Abstract
We examined the ventilatory response of the spiny dogfish, to elevated internal or environmental ammonia. Sharks were injected via arterial catheters with ammonia solutions or their Na salt equivalents sufficient to increase plasma total ammonia concentration [TAmm]a by 3-5 fold from 145±21μM to 447±150μM using NH4HCO3 and a maximum of 766±100μM using (NH4)2SO4. (NH4)2SO4 caused a small increase in ventilation frequency (+14%) and a large increase in amplitude (+69%), while Na2SO4 did not. However, CO2 partial pressure (PaCO2) also increased and arterial pHa and plasma bicarbonate concentration ([HCO3(-)]a) decreased. NH4HCO3 caused a smaller increase in plasma ammonia resulting in a smaller but significant, short lived increases in ventilation frequency (+6%) and amplitude (36%), together with a rise in PaCO2 and [HCO3(-)]a. Injection with NaHCO3 which increased pHa and [HCO3(-)]a did not change ventilation. Plasma ammonia concentration correlated significantly with ventilation amplitude, while ventilation frequency showed a (negative) correlation with pHa. Exposure to high environmental ammonia (1500μM NH4HCO3) did not induce changes in ventilation until plasma [TAmm]a increased and ventilation amplitude (but not frequency) increased in parallel. We conclude that internal ammonia stimulates ventilation in spiny dogfish, especially amplitude or stroke volume, while environmental ammonia only stimulates ventilation after ammonia diffuses into the bloodstream.
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Affiliation(s)
- Gudrun De Boeck
- Bamfield Marine Sciences Centre, 100 Pachena Rd, Bamfield, British Columbia V0R 1B0, Canada; SPHERE, Department of Biology, University of Antwerp, Groenenborgerlaan 171, B-2020 Antwerp, Belgium.
| | - Chris M Wood
- Bamfield Marine Sciences Centre, 100 Pachena Rd, Bamfield, British Columbia V0R 1B0, Canada; Department of Biology, McMaster University, Hamilton, Ontario L8S 4K1, Canada; Division of Marine Biology and Fisheries, Rosenstiel School of Marine and Atmospheric Science, University of Miami, Miami, FL 33149, USA; Department of Zoology, University of British Columbia, Vancouver, British Columbia V6T 1Z4, Canada
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Miller S, Pollack J, Bradshaw J, Kumai Y, Perry SF. Cardiac responses to hypercapnia in larval zebrafish (Danio rerio): the links between CO2 chemoreception, catecholamines and carbonic anhydrase. ACTA ACUST UNITED AC 2014; 217:3569-78. [PMID: 25063853 DOI: 10.1242/jeb.107987] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Abstract
The ontogeny of carbon dioxide (CO2) sensing in zebrafish (Danio rerio) has not been examined. In this study, CO2-mediated increases in heart rate were used to gauge the capacity of zebrafish larvae to sense CO2. CO2 is thought to be detected via neuroepithelial cells (NECs), which are homologous to mammalian carotid body glomus cells. Larvae at 5 days post-fertilization (d.p.f.) exhibited tachycardia when exposed for 30 min to 0.75% CO2 (~5.63 mmHg); at 7 d.p.f., tachycardia was elicited by 0.5% CO2 (~3.75 mmHg). Based on pharmacological evidence using β-adrenergic receptor (β-AR) antagonists, and confirmed by β1-AR translational gene knockdown using morpholinos, the reflex tachycardia accompanying hypercapnia was probably mediated by the interaction of catecholamines with cardiac β1 receptors. Because the cardiac response to hypercapnia was abolished by the ganglionic blocker hexamethonium, it is probable that the reflex cardio-acceleration was mediated by catecholamines derived from sympathetic adrenergic neurons. Owing to its likely role in facilitating intracellular acidification during exposure to hypercapnia, it was hypothesized that carbonic anhydrase (CA) is involved in CO2 sensing, and that inhibition of CA activity would blunt the downstream responses. Indeed, the cardiac response to hypercapnia (0.75% CO2) was reduced in fish at 5 d.p.f. exposed to acetazolamide, a CA inhibitor, and in fish experiencing zCAc (CA2-like a) knockdown. Successful knockdown of zCAc was confirmed by CA activity measurements, western blotting and immunocytochemistry. Co-injection of embryos with zCAc morpholino and mRNA modified at the morpholino binding site restored normal levels of CA activity and protein levels, and restored (rescued) the usual cardiac responses to hypercapnia. These data, combined with the finding that zCAc is expressed in NECs located on the skin, suggest that the afferent limb of the CO2-induced cardiac reflex in zebrafish larvae is initiated by coetaneous CO2-sensing neuroepithelial cells.
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Affiliation(s)
- Scott Miller
- Department of Biology, University of Ottawa, 30 Marie Curie, Ottawa, ON, Canada, K1N 6N5
| | - Jacob Pollack
- Department of Biology, University of Ottawa, 30 Marie Curie, Ottawa, ON, Canada, K1N 6N5
| | - Julia Bradshaw
- Department of Fisheries and Oceans, Pacific Biological Station, 3190 Hammond Bay Road, Nanaimo, BC, Canada, V9T 6N7
| | - Yusuke Kumai
- Department of Physiology and Biophysics, Case Western Reserve University School of Medicine, 10900 Euclid Avenue, Cleveland, OH 44106, USA
| | - Steve F Perry
- Department of Biology, University of Ottawa, 30 Marie Curie, Ottawa, ON, Canada, K1N 6N5
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11
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Mechanisms and consequences of carbon dioxide sensing in fish. Respir Physiol Neurobiol 2012; 184:309-15. [DOI: 10.1016/j.resp.2012.06.013] [Citation(s) in RCA: 45] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2012] [Revised: 06/09/2012] [Accepted: 06/10/2012] [Indexed: 11/20/2022]
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12
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Milsom WK. New insights into gill chemoreception: Receptor distribution and roles in water and air breathing fish. Respir Physiol Neurobiol 2012; 184:326-39. [DOI: 10.1016/j.resp.2012.07.013] [Citation(s) in RCA: 69] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2012] [Revised: 07/15/2012] [Accepted: 07/17/2012] [Indexed: 12/16/2022]
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13
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Gilmour KM. New insights into the many functions of carbonic anhydrase in fish gills. Respir Physiol Neurobiol 2012; 184:223-30. [PMID: 22706265 DOI: 10.1016/j.resp.2012.06.001] [Citation(s) in RCA: 40] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2012] [Revised: 05/31/2012] [Accepted: 06/01/2012] [Indexed: 01/25/2023]
Abstract
Carbonic anhydrase (CA) is a zinc metalloenzyme that catalyzes the reversible reactions of carbon dioxide and water: CO(2) + H(2)O ↔ H(+) + HCO(3)(-). It has long been recognized that CA is abundant in the fish gill, with attention focused on the role of CA in catalyzing the hydration of CO(2) to provide H(+) and HCO(3)(-) for the branchial ion transport processes that underlie systemic ionic and acid-base regulation. Recent work has explored the diversity of CA isoforms in the fish gill. By linking these isoforms to different cell types in the gill, and by exploiting the diversity of fish species available for study, this work is increasing our understanding of the many roles that CA plays in the fish gill. In particular, recent work has revealed that fish utilize more than one model of CO(2) excretion, that to understand the role of CA and the gill in ionic regulation and acid-base balance means characterizing the transporter and CA complement of individual cell types, and that CA plays roles in branchial sensory mechanisms. The goal of this brief review is to summarize these new developments, while at the same time highlighting key areas in which further research is needed.
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Affiliation(s)
- Kathleen M Gilmour
- Department of Biology, University of Ottawa, 30 Marie Curie, Ottawa, ON, K1N 6N5, Canada.
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14
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Esbaugh AJ, Heuer R, Grosell M. Impacts of ocean acidification on respiratory gas exchange and acid-base balance in a marine teleost, Opsanus beta. J Comp Physiol B 2012; 182:921-34. [PMID: 22581071 DOI: 10.1007/s00360-012-0668-5] [Citation(s) in RCA: 135] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2012] [Revised: 04/11/2012] [Accepted: 04/14/2012] [Indexed: 11/27/2022]
Abstract
The oceanic carbonate system is changing rapidly due to rising atmospheric CO(2), with current levels expected to rise to between 750 and 1,000 μatm by 2100, and over 1,900 μatm by year 2300. The effects of elevated CO(2) on marine calcifying organisms have been extensively studied; however, effects of imminent CO(2) levels on teleost acid-base and respiratory physiology have yet to be examined. Examination of these physiological processes, using a paired experimental design, showed that 24 h exposure to 1,000 and 1,900 μatm CO(2) resulted in a characteristic compensated respiratory acidosis response in the gulf toadfish (Opsanus beta). Time course experiments showed the onset of acidosis occurred after 15 min of exposure to 1,900 and 1,000 μatm CO(2), with full compensation by 2 and 4 h, respectively. 1,900-μatm exposure also resulted in significantly increased intracellular white muscle pH after 24 h. No effect of 1,900 μatm was observed on branchial acid flux; however, exposure to hypercapnia and HCO(3)(-) free seawater compromised compensation. This suggests branchial HCO(3)(-) uptake rather than acid extrusion is part of the compensatory response to low-level hypercapnia. Exposure to 1,900 μatm resulted in downregulation in branchial carbonic anhydrase and slc4a2 expression, as well as decreased Na(+)/K(+) ATPase activity after 24 h of exposure. Infusion of bovine carbonic anhydrase had no effect on blood acid-base status during 1,900 μatm exposures, but eliminated the respiratory impacts of 1,000 μatm CO(2). The results of the current study clearly show that predicted near-future CO(2) levels impact respiratory gas transport and acid-base balance. While the full physiological impacts of increased blood HCO(3)(-) are not known, it seems likely that chronically elevated blood HCO(3)(-) levels could compromise several physiological systems and furthermore may explain recent reports of increased otolith growth during exposure to elevated CO(2).
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Affiliation(s)
- Andrew J Esbaugh
- Division of Marine Biology and Fisheries, Rosenstiel School of Marine and Atmospheric Science, University of Miami, 4600 Rickenbacker Causeway, Miami, FL 33149, USA.
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Baker DW, Hanson LM, Farrell AP, Brauner CJ. Exceptional CO₂ tolerance in white sturgeon (Acipenser transmontanus) is associated with protection of maximum cardiac performance during hypercapnia in situ. Physiol Biochem Zool 2011; 84:239-48. [PMID: 21527814 DOI: 10.1086/660038] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
Abstract
White sturgeon rank among the most CO₂-tolerant fish species examined to date. We investigated whether this exceptional CO₂ tolerance extended to the heart, an organ generally viewed as acidosis intolerant. Maximum cardiac output (Q(max)) and maximum cardiac power output (PO(max)) were assessed using a working, perfused, in situ heart preparation. Exposure to a Pco₂ of 3 kPa for 20 min had no significant effect on maximum cardiac performance, while exposure to 6-kPa Pco₂ reduced heart rate, Q(max), PO(max), and rate of ventricular force generation (F(O)) by 23%, 28%, 26%, and 18%, respectively; however, full recovery was observed in all these parameters upon return to control conditions. These modest impairments during exposure to 6-kPa Pco₂ were associated with partially compensated intracellular ventricular acidosis. Maximum adrenergic stimulation (500 nmol L⁻¹ adrenaline) during 6-kPa Pco₂ protected maximum cardiac performance via increased inotropy (force of contraction) without affecting heart rate. Exposure to higher CO₂ levels associated with morbidity in vivo (i.e., 8-kPa Pco₂) induced arrhythmia and a reduction in stroke volume during power assessment. Clearly, white sturgeon hearts are able to increase cardiac performance during severe hypercapnia that is lethal to other fishes. Future work focusing on atypical aspects of sturgeon cardiac function, including the lack of chronotropic response to adrenergic stimulation during hypercapnia, is warranted.
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Affiliation(s)
- Daniel W Baker
- School of Biological Science, University of Auckland, Private Bag 92019, Auckland 1142, New Zealand.
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16
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de Lima Boijink C, Florindo LH, Leite CAC, Kalinin AL, Milsom WK, Rantin FT. Hypercarbic cardiorespiratory reflexes in the facultative air-breathing fish jeju (Hoplerythrinus unitaeniatus): the role of branchial CO2 chemoreceptors. J Exp Biol 2010; 213:2797-807. [DOI: 10.1242/jeb.040733] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
SUMMARY
The aim of the present study was to determine the roles that externally versus internally oriented CO2/H+-sensitive chemoreceptors might play in promoting cardiorespiratory responses to environmental hypercarbia in the air-breathing fish, Hoplerythrinus unitaeniatus (jeju). Fish were exposed to graded hypercarbia (1, 2.5, 5, 10 and 20% CO2) and also to graded levels of environmental acidosis (pH ~7.0, 6.0, 5.8, 5.6, 5.3 and 4.7) equal to the pH levels of the hypercarbic water to distinguish the relative roles of CO2versus H+. We also injected boluses of CO2-equilibrated solutions (5, 10 and 20% CO2) and acid solutions equilibrated to the same pH as the CO2 boluses into the caudal vein (internal) and buccal cavity (external) to distinguish between internal and external stimuli. The putative location of the chemoreceptors was determined by bilateral denervation of branches of cranial nerves IX (glossopharyngeal) and X (vagus) to the gills. The data indicate that the chemoreceptors eliciting bradycardia, hypertension and gill ventilatory responses (increased frequency and amplitude) to hypercarbia are exclusively branchial, externally oriented and respond specifically to changes in CO2 and not H+. Those involved in producing the cardiovascular responses appeared to be distributed across all gill arches while those involved in the gill ventilatory responses were located primarily on the first gill arch. Higher levels of aquatic CO2 depressed gill ventilation and stimulated air breathing. The chemoreceptors involved in producing air breathing in response to hypercarbia also appeared to be branchial, distributed across all gill arches and responded specifically to changes in aquatic CO2. This would suggest that chemoreceptor groups with different orientations (blood versus water) are involved in eliciting air-breathing responses to hypercarbia in jeju.
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Affiliation(s)
- Cheila de Lima Boijink
- Departament of Physiological Sciences, Federal University of São Carlos, 13565-905 São Carlos, SP, Brazil
| | - Luiz Henrique Florindo
- Departament of Zoology and Botany, Aquaculture Center (CAUNESP), São Paulo State University – UNESP, 15054-000, São José do Rio Preto, SP, Brazil
- National Institute of Science and Technology – Comparative Physiology (FAPESP/CNPq), Brazil
| | - Cleo A. Costa Leite
- Departament of Physiological Sciences, Federal University of São Carlos, 13565-905 São Carlos, SP, Brazil
- National Institute of Science and Technology – Comparative Physiology (FAPESP/CNPq), Brazil
| | - Ana Lúcia Kalinin
- Departament of Physiological Sciences, Federal University of São Carlos, 13565-905 São Carlos, SP, Brazil
- National Institute of Science and Technology – Comparative Physiology (FAPESP/CNPq), Brazil
| | - William K. Milsom
- Department of Zoology, University of British Columbia, Vancouver, BC, Canada, V6T 1Z4
| | - Francisco Tadeu Rantin
- Departament of Physiological Sciences, Federal University of São Carlos, 13565-905 São Carlos, SP, Brazil
- National Institute of Science and Technology – Comparative Physiology (FAPESP/CNPq), Brazil
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Milsom WK. The phylogeny of central chemoreception. Respir Physiol Neurobiol 2010; 173:195-200. [PMID: 20594933 DOI: 10.1016/j.resp.2010.05.022] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2010] [Revised: 05/27/2010] [Accepted: 05/27/2010] [Indexed: 11/18/2022]
Abstract
Respiratory chemoreceptors responsive to changes in CO(2)/H(+) appear to be present in all vertebrates from fish to birds and mammals. They appear to have arisen first in the periphery sensitive to the external environment. Thus, in most fish CO(2)/H(+) chemoreceptors reside primarily in the gills and respond to changes in aquatic rather than arterial P(CO)₂ . In the air-breathing tetrapods (amphibians, mammals, reptiles and birds), the branchial arches regress developmentally and the derivatives of the branchial arteries are now exclusively internal. The receptors associated with these arteries now sense only arterial (not environmental) P(CO)₂/pH . Central CO(2)/H(+) chemoreception also appears to have arisen with the advent of air breathing, presumably as a second line of defense. These receptors may have arisen multiple times in association with several (but not all) of the independent origins of air breathing in fishes. There is strong evidence for multiple central sites of CO(2)/H(+) sensing, at least in amphibians and mammals, suggesting that it may not only have originated multiple times in different species but also multiple times within a single species.
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Affiliation(s)
- W K Milsom
- Department of Zoology, University of British Columbia, Vancouver, BC, Canada.
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Qin Z, Lewis JE, Perry SF. Zebrafish (Danio rerio) gill neuroepithelial cells are sensitive chemoreceptors for environmental CO2. J Physiol 2010; 588:861-72. [PMID: 20051495 DOI: 10.1113/jphysiol.2009.184739] [Citation(s) in RCA: 77] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022] Open
Abstract
Adult zebrafish exhibit hyperventilatory responses to absolute environmental CO(2) levels as low as 0.13% ( mmHg), more than an order of magnitude lower than the typical arterial levels (40 mmHg) monitored by the mammalian carotid body. The sensory basis underlying the ability of fish to detect and respond to low ambient CO(2) levels is not clear. Here, we show that the neuroepithelial cells (NECs) of the zebrafish gill, known to sense O(2) levels, also respond to low levels of CO(2). An electrophysiological characterization of this response using both current and voltage clamp protocols revealed that for increasing CO(2) levels, a background K(+) channel was inhibited, resulting in a partial pressure-dependent depolarization of the NEC. To elucidate the signalling pathway underlying K(+) channel inhibition, we used immunocytochemistry to show that these NECs express carbonic anhydrase (CA), an enzyme involved in CO(2) sensing in the mammalian carotid body. Further, the NEC response to CO(2) (magnitude of membrane depolarization and time required to achieve maximal response), under conditions of constant pH, was reduced by 50% by the CA-inhibitor acetazolamide. This suggests that the CO(2) detection mechanism involves an intracellular sensor that is responsive to the rate of acidification associated with the hydration of CO(2) and which does not require a change of extracellular pH. Because some cells that were responsive to increasing also responded to hypoxia with membrane depolarization, the present results demonstrate that a subset of the NECs in the zebrafish gill are bimodal sensors of CO(2) and O(2).
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Affiliation(s)
- Z Qin
- Department of Biology, University of Ottawa, 30 Marie Curie, Ottawa, ON, Canada
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19
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Duncan W, da Costa O, Sakuragui M, Fernandes M. Functional Morphology of the Gill in Amazonian Freshwater Stingrays (Chondrichthyes: Potamotrygonidae): Implications for Adaptation to Freshwater. Physiol Biochem Zool 2010; 83:19-32. [DOI: 10.1086/605458] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
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Perry S, Vulesevic B, Braun M, Gilmour K. Ventilation in Pacific hagfish (Eptatretus stoutii) during exposure to acute hypoxia or hypercapnia. Respir Physiol Neurobiol 2009; 167:227-34. [DOI: 10.1016/j.resp.2009.04.025] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2009] [Revised: 04/28/2009] [Accepted: 04/30/2009] [Indexed: 10/20/2022]
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21
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Mendonça PC, Gamperl AK. Nervous and humoral control of cardiac performance in the winter flounder(Pleuronectes americanus). J Exp Biol 2009; 212:934-44. [DOI: 10.1242/jeb.027680] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
Abstract
SUMMARY
Previous studies have suggested that flatfish lack adrenergic cardiac innervation and have a limited humoral adrenergic stress response. However,data on neurohormonal control of flatfish cardiac function is scarce, and has never been directly studied in vivo. Hence, we (1) injected neural and humoral antagonists into flounder (Pleuronectes americanus) in vivo to determine the contribution of autonomic innervation and circulating catecholamines to the control of resting cardiac function; (2)measured pre- and post-stress (90 s chase) catecholamine levels in this species; and (3) constructed in vivo catecholamine dose–response curves for cardiovascular function based on the results of the second experiment. In addition, we quantified the density(Bmax) and ligand-binding affinity(Kd) of flounder ventricular cell-surfaceβ-adrenoreceptors, and established whether they were ofβ 1 or β2 subtype using pharmacological antagonists. The cholinergic contribution to resting flounder heart rate was comparable to other teleosts (cholinergic tonus 26%). Interestingly, however,bretylium increased heart rate, resulting in a negative resting adrenergic tonus (–11.9%), and we were unable to demonstrate that catecholamines supported cardiac function at rest or at circulating concentrations approximating those following an exhaustive chase (adrenaline, 21 nmol l–1; noradrenaline, 14 nmol l–1). Myocardial Bmax was very high in the flounder (252.8 fmol mg–1 protein), and it appears that flounder ventricularβ-adrenoreceptors are predominantly of the β2 subtype[based on the inability of atenolol to displace [3H]CGP from theβ-adrenoreceptors, and the IC50 value for ICI 118551(1.91×10–6 mol l–1)]. However, the extremely low affinity (Kd 1.02 nmol l–1)for these receptors raises the possibility that the flounder heart is also populated by β3-adrenoreceptors.
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Affiliation(s)
- Paula C. Mendonça
- Ocean Sciences Centre, Memorial University, St John's, Canada, NL A1C 5S7
| | - A. Kurt Gamperl
- Ocean Sciences Centre, Memorial University, St John's, Canada, NL A1C 5S7
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22
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Perry S, Euverman R, Wang T, Loong A, Chew S, Ip Y, Gilmour K. Control of breathing in African lungfish (Protopterus dolloi): A comparison of aquatic and cocooned (terrestrialized) animals. Respir Physiol Neurobiol 2008; 160:8-17. [DOI: 10.1016/j.resp.2007.06.015] [Citation(s) in RCA: 52] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2007] [Revised: 06/28/2007] [Accepted: 06/29/2007] [Indexed: 11/15/2022]
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23
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Janech MG, Fitzgibbon WR, Ploth DW, Lacy ER, Miller DH. Effect of low environmental salinity on plasma composition and renal function of the Atlantic stingray, a euryhaline elasmobranch. Am J Physiol Renal Physiol 2006; 291:F770-80. [PMID: 16609153 DOI: 10.1152/ajprenal.00026.2006] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Marine elasmobranchs maintain internal osmolality higher than their external environment, resulting in an osmotic gradient for branchial water uptake. This gradient is markedly increased in low-salinity habitats. The subsequent increase in water uptake presents a challenge to volume homeostasis. The Atlantic stingray is a marine elasmobranch that inhabits a remarkable range of environmental salinities. We hypothesized that the ability of these stingrays to regulate fluid volume in low-salinity environments is due primarily to a renal glomerular and tubular functional reserve. We tested this hypothesis by measuring renal excretory function after a rapid and sustained 50% reduction in the osmolality of the external medium. Atlantic stingrays were maintained in harbor water [control salinity (CS) ∼850 mosmol/kgH2O] for 1 wk. Rays were then either transferred to diluted harbor water [low salinity (LS) ∼440 mosmol/kgH2O] or maintained in CS for a further 24 h. Renal excretory function was markedly higher in the rays subjected to low salinity. Glomerular filtration rate was threefold higher and urine flow rate ninefold higher in the LS group. The clearance of solute-free water was greater, and solute-free water comprised a significantly larger proportion of the urine output for the stingrays transferred to dilute harbor water. We conclude that 1) the kidneys of Atlantic stingrays have a remarkable glomerular and tubular functional reserve, and 2) the marked increase in renal function attenuates the increase in fluid volume when these fish move into low-salinity habitats.
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Affiliation(s)
- Michael G Janech
- Grice Marine Laboratory, College of Charleston, Charleston, SC, USA
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24
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Perry SF, Gilmour KM. Acid-base balance and CO2 excretion in fish: unanswered questions and emerging models. Respir Physiol Neurobiol 2006; 154:199-215. [PMID: 16777496 DOI: 10.1016/j.resp.2006.04.010] [Citation(s) in RCA: 181] [Impact Index Per Article: 10.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2005] [Revised: 04/14/2006] [Accepted: 04/15/2006] [Indexed: 11/22/2022]
Abstract
Carbon dioxide (CO(2)) excretion and acid-base regulation in fish are linked, as in other animals, though the reversible reactions of CO(2) and the acid-base equivalents H(+) and HCO(3)(-): CO(2)+H(2)O<-->H(+)+HCO(3)(-). These relationships offer two potential routes through which acid-base disturbances may be regulated. Respiratory compensation involves manipulation of ventilation so as to retain CO(2) or enhance CO(2) loss, with the concomitant readjustment of the CO(2) reaction equilibrium and the resultant changes in H(+) levels. In metabolic compensation, rates of direct H(+) and HCO(3)(-) exchange with the environment are manipulated to achieve the required regulation of pH; in this case, hydration of CO(2) yields the necessary H(+) and HCO(3)(-) for exchange. Because ventilation in fish is keyed primarily to the demands of extracting O(2) from a medium of low O(2) content, the capacity to utilize respiratory compensation of acid-base disturbances is limited and metabolic compensation across the gill is the primary mechanism for re-establishing pH balance. The contribution of branchial acid-base exchanges to pH compensation is widely recognized, but the molecular mechanisms underlying these exchanges remain unclear. The relatively recent application of molecular approaches to this question is generating data, sometimes conflicting, from which models of branchial acid-base exchange are gradually emerging. The critical importance of the gill in acid-base compensation in fish, however, has made it easy to overlook other potential contributors. Recently, attention has been focused on the role of the kidney and particularly the molecular mechanisms responsible for HCO(3)(-) reabsorption. It is becoming apparent that, at least in freshwater fish, the responses of the kidney are both flexible and essential to complement the role of the gill in metabolic compensation. Finally, while respiratory compensation in fish is usually discounted, the few studies that have thoroughly characterized ventilatory responses during acid-base disturbances in fish suggest that breathing may, in fact, be adjusted in response to pH imbalances. How this is accomplished and the role it plays in re-establishing acid-base balance are questions that remain to be answered.
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Affiliation(s)
- S F Perry
- Department of Biology and Centre for Advanced Research in Environmental Genomics, University of Ottawa, 30 Marie Curie, Ottawa, Ont., Canada.
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Perry SF, Desforges PR. Does bradycardia or hypertension enhance gas transfer in rainbow trout (Oncorhynchus mykiss)? Comp Biochem Physiol A Mol Integr Physiol 2006; 144:163-72. [PMID: 16574450 DOI: 10.1016/j.cbpa.2006.02.026] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2005] [Revised: 02/14/2006] [Accepted: 02/18/2006] [Indexed: 11/29/2022]
Abstract
Experiments were conducted to test the hypothesis that branchial gas transfer is enhanced in rainbow trout during hypoxia or hypercarbia by bradycardia and systemic vasoconstriction. Gas transfer was indirectly assessed by continuous monitoring of arterial blood gases, PaO2 and PaCO2. Cardiac frequency was maximally decreased by 34.9+/-4.3 and 8.6+/-3.2 bpm in hypoxic and hypercarbic fish, respectively. Pre-treating fish with atropine (1micromol kg(-1)) attenuated or abolished the bradycardia during hypoxia and hypercarbia, respectively. However, there were no significant differences in the arterial blood gases between the control and atropinized fish. Dorsal aortic blood pressure was increased maximally by 11.3+/-2.8 and 17.7+/-2.0mm Hg in the hypoxic and hypercarbic fish. Pre-treatment of fish with prazosin (2.4micromol kg(-1)) prevented these increases in blood pressure. Blood gases were unaltered by prazosin treatment in the hypercarbic fish. However, in the hypoxic fish, gas transfer appeared to be impaired by prazosin on the basis of lowered PaO2 (by approximately 35 mm Hg compared to control fish) and increased PaCO2 (by approximately 0.3mm Hg). Because the normal hyperventilatory response to hypoxia was prevented by prazosin, it is possible that the impairment of gas transfer was related to inadequate ventilation rather than to any differences in the pressor response. The present results provide no evidence that gas transfer in rainbow trout is enhanced by bradycardia nor do they reveal any obvious benefit associated with the increases in blood pressure that accompany hypoxia and hypercarbia.
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Affiliation(s)
- S F Perry
- Department of Biology, University of Ottawa, 10 Marie Curie, Ottawa, ON, Canada K1N 6N5.
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26
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Melzner F, Bock C, Pörtner HO. Temperature-dependent oxygen extraction from the ventilatory current and the costs of ventilation in the cephalopod Sepia officinalis. J Comp Physiol B 2006; 176:607-21. [PMID: 16710699 DOI: 10.1007/s00360-006-0084-9] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2006] [Revised: 03/23/2006] [Accepted: 03/29/2006] [Indexed: 11/30/2022]
Abstract
Earlier work found cuttlefish (Sepia officinalis) ventilatory muscle tissue to progressively switch to an anaerobic mode of energy production at critical temperatures (T (c)) of 7.0 and 26.8 degrees C. These findings suggested that oxygen availability limits thermal tolerance. The present study was designed to elucidate whether it is the ventilatory apparatus that sets critical temperature thresholds during acute thermal stress. Routine metabolic rate (rmr) rose exponentially between 11 and 23 degrees C, while below (8 degrees C) and above (26 degrees C) this temperature range, rmr was significantly depressed. Ventilation frequency (f (V)) and mean mantle cavity pressure (MMP) followed an exponential relationship within the entire investigated temperature range (8-26 degrees C). Oxygen extraction from the ventilatory current (EO(2)) decreased in a sigmoidal fashion with temperature, falling from > 90% at 8 degrees C to 32% at 26 degrees C. Consequently, ventilatory minute volume (MV(V)) increased by a factor of 20 from 7 to 150% body weight min(-1) in the same temperature interval. Increases in MMP and MV(V) resulted in ventilatory muscle power output (P (out)) increasing by a factor of > 80 from 0.03 to 2.4 mW kg(-1) animal. Nonetheless, costs for ventilatory mechanics remain below 1.5% rmr in the natural thermal window of the population (English Channel, 9-17 degrees C), owing to very low MMPs of < 0.05 kPa driving the ventilatory stream, and may maximally rise to 8.6% rmr at 26 degrees C. Model calculations suggest that the ventilatory system can maintain high arterial PO(2) values of > 14 kPa over the entire temperature interval. We therefore conclude that the cuttlefish ventilation system is probably not limiting oxygen transfer during acute thermal stress. Depression of rmr, well before critical temperatures are being reached, is likely caused by circulatory capacity limitations and not by fatigue of ventilatory muscle fibres.
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Affiliation(s)
- Frank Melzner
- Alfred-Wegener-Institute for Marine and Polar Research, Am Handelshafen 12, 27570 Bremerhaven, Germany.
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27
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Aggio JF, de Freitas JC. Physiological and behavioral effects of chemoreceptors located in different body parts of the swimming crab Callinectes danae. Comp Biochem Physiol A Mol Integr Physiol 2006; 146:653-60. [PMID: 16762574 DOI: 10.1016/j.cbpa.2006.04.021] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2005] [Revised: 04/21/2006] [Accepted: 04/23/2006] [Indexed: 10/24/2022]
Abstract
By perfusing their branchial chambers with filtered seawater, we have developed a preparation that allows us to maintain the swimming crab Callinectes danae outside water without any major effects on its cardiac activity. This in turn allowed us to selectively stimulate chemoreceptors located in different body parts, and specifically to discriminate between the receptors located in the branchial chambers and those located in the oral region (mainly in the mouthparts, antennules and antennae). We show that a taurine solution can evoke bradycardia when applied to the oral region or to a combination of the oral region and the branchial chambers. Although the precise localization of the oral region receptors involved remains to be determined, ablation experiments show that the olfactory organs (i.e., the antennules) are not involved. Finally, we show that although stimulating the pereiopods has no effect on the animals' cardiac activity it causes the animals to move, putatively to try to grasp a piece of food, a reaction not evoked by stimulating the gills or the oral regions. Our results lend support to the idea that chemoreceptors located in different parts of the body play different functional roles in decapod crustaceans.
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Affiliation(s)
- Juan F Aggio
- Instituto de Biociências, Universidade de São Paulo, Brazil.
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28
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Gilmour KM, Perry SF. Branchial Chemoreceptor Regulation of Cardiorespiratory Function. FISH PHYSIOLOGY 2006. [DOI: 10.1016/s1546-5098(06)25003-9] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
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Gilmour KM, Milsom WK, Rantin FT, Reid SG, Perry SF. Cardiorespiratory responses to hypercarbia in tambaquiColossoma macropomum: chemoreceptor orientation and specificity. J Exp Biol 2005; 208:1095-107. [PMID: 15767310 DOI: 10.1242/jeb.01480] [Citation(s) in RCA: 42] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
SUMMARYExperiments were carried out to test the hypothesis that ventilatory and cardiovascular responses to hypercarbia (elevated water PCO2) in the tambaqui Colossoma macropomum are stimulated by externally oriented receptors that are sensitive to water CO2 tension as opposed to water pH. Cardiorespiratory responses to acute hypercarbia were evaluated in both the absence and presence of internal hypercarbia (elevated blood PCO2), achieved by treating fish with the carbonic anhydrase inhibitor acetazolamide. Exposure to acute hypercarbia (15 min at each level, final water CO2 tensions of 7.2,15.5 and 26.3 mmHg) elicited significant increases in ventilation frequency(at 26.3 mmHg, a 42% increase over the normocarbic value) and amplitude(128%), together with a fall in heart rate (35%) and an increase in cardiac stroke volume (62%). Rapid washout of CO2 from the water reversed these effects, and the timing of the changes in cardiorespiratory variables corresponded more closely to the fall in water PCO2(PwCO2) than to that in blood PCO2(PaCO2). Similar responses to acute hypercarbia (15 min,final PwCO2 of 13.6 mmHg) were observed in acetazolamide-treated (30 mg kg-1) tambaqui. Acetazolamide treatment itself, however, increased PaCO2 (from 4.81±0.58 to 13.83±0.91 mmHg, mean ± s.e.m.; N=8) in the absence of significant change in ventilation, heart rate or cardiac stroke volume. The lack of response to changes in blood PCO2 and/or pH were confirmed by comparing responses to the bolus injection of hypercarbic saline(5% or 10% CO2; 2 ml kg-1) into the caudal vein with those to the injection of CO2-enriched water (1%, 3%, 5% or 10%CO2; 50 ml kg-1) into the buccal cavity. Whereas injections of hypercarbic saline were ineffective in eliciting cardiorespiratory responses, changes in ventilation and cardiovascular parameters accompanied injection of CO2-laden water into the mouth. Similar injections of CO2-free water acidified to the corresponding pH of the hypercarbic water (pH 6.3, 5.6, 5.3 or 4.9, respectively) generally did not stimulate cardiorespiratory responses. These results are in agreement with the hypothesis that in tambaqui, externally oriented chemoreceptors that are predominantly activated by increases in water PCO2,rather than by accompanying decreases in water pH, are linked to the initiation of cardiorespiratory responses to hypercarbia.
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Affiliation(s)
- K M Gilmour
- Department of Physiological Sciences, Federal University of São Carlos, Via Washington Luiz km 235, São Carlos, SP 13565-905, Brazil.
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Evans DH, Piermarini PM, Choe KP. The Multifunctional Fish Gill: Dominant Site of Gas Exchange, Osmoregulation, Acid-Base Regulation, and Excretion of Nitrogenous Waste. Physiol Rev 2005; 85:97-177. [PMID: 15618479 DOI: 10.1152/physrev.00050.2003] [Citation(s) in RCA: 1599] [Impact Index Per Article: 84.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
The fish gill is a multipurpose organ that, in addition to providing for aquatic gas exchange, plays dominant roles in osmotic and ionic regulation, acid-base regulation, and excretion of nitrogenous wastes. Thus, despite the fact that all fish groups have functional kidneys, the gill epithelium is the site of many processes that are mediated by renal epithelia in terrestrial vertebrates. Indeed, many of the pathways that mediate these processes in mammalian renal epithelial are expressed in the gill, and many of the extrinsic and intrinsic modulators of these processes are also found in fish endocrine tissues and the gill itself. The basic patterns of gill physiology were outlined over a half century ago, but modern immunological and molecular techniques are bringing new insights into this complicated system. Nevertheless, substantial questions about the evolution of these mechanisms and control remain.
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Affiliation(s)
- David H Evans
- Department of Zoology, University of Florida, Gainesville 32611, USA.
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Perry SF, Reid SG. Cardiorespiratory adjustments during hypercarbia in rainbow troutOncorhynchus mykissare initiated by external CO2receptors on the first gill arch. J Exp Biol 2002; 205:3357-65. [PMID: 12324545 DOI: 10.1242/jeb.205.21.3357] [Citation(s) in RCA: 52] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
SUMMARYExperiments were performed to test the hypothesis that the marked ventilatory and cardiovascular responses to hypercarbia in rainbow trout Oncorhynchus mykiss arise from specific stimulation of chemoreceptors localised to the first gill arch. This was accomplished by measuring cardiorespiratory variables during acute hypercarbia (20 min at PCO2=8 mmHg; 1 mmHg=0.133 kPa) in fish subjected to selective bilateral extirpation of the first gill arch. The cardiovascular responses to hypercarbia in the intact fish included a significant bradycardia (from 75.0±1.6 to 69.0±2.0 beats min-1; means ± S.E.M.; N=16), an increase in dorsal aortic blood pressure (from 30.8±1.5 to 41.9±2.5 mmHg; N=16) and a rise in systemic vascular resistance (from 1.1±0.1 to 1.4±0.1 mmHg ml-1 kg-1 min-1; N=16). Removal of the first gill arch or pre-treatment with the muscarinic receptor antagonist atropine prevented the hypercarbic bradycardia without affecting the pressure or resistance responses. Correlation analysis,however, revealed shallow but significant inverse relationships between water PCO2 and cardiac frequency in both atropinised(r2=0.75) and gill-extirpated(r2=0.90) fish, suggesting a direct mild effect of CO2 on cardiac function. The ventilatory response to hypercarbia in the intact fish consisted of an increase in ventilation amplitude (from 0.62±0.06 to 1.0±0.13 cm; N=16) with no change in breathing frequency. Removal of the first gill arch lowered resting breathing frequency and prevented the statistically significant elevation of breathing amplitude. Gill extirpation, however, did not totally abolish the positive correlation between water PCO2 and ventilation amplitude (r2=0.84), suggesting the presence of additional(although less important) chemoreceptive sites that are not confined to the first gill arch. Plasma catecholamine levels were elevated during hypercarbia,and this response was unaffected by prior gill extirpation.To assess whether the CO2 chemoreceptors of the first gill arch were sensing water and/or blood PCO2, bolus injections of CO2-enriched water or saline were made into the buccal cavity or caudal vein, respectively. Injections of CO2-enriched water to preferentially stimulate external receptors evoked catecholamine release and cardiorespiratory responses that closely resembled the responses to hypercarbia. As in hypercarbia, extirpation of the first gill arch prevented the bradycardia and the increase in ventilation amplitude associated with externally injected CO2-enriched water. Except for a slight decrease in cardiac frequency (from 73.0±2.8 to 70.3±3.5 beats min-1; N=11), injection of CO2-enriched saline to preferentially stimulate internal chemoreceptors did not affect any measured variable. Taken together, these data indicate that, in rainbow trout, the bradycardia and hyperventilation associated with hypercarbia are triggered largely by external CO2chemoreceptors confined to the first gill arch.
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Affiliation(s)
- Steve F Perry
- Department of Biology, University of Ottawa, 50 Marie Curie, Ontario, Canada, K1N 6N5.
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Perry SF, Gilmour KM. Sensing and transfer of respiratory gases at the fish gill. THE JOURNAL OF EXPERIMENTAL ZOOLOGY 2002; 293:249-63. [PMID: 12115900 DOI: 10.1002/jez.10129] [Citation(s) in RCA: 87] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
The gill is both a site of gas transfer and an important location of chemoreception or gas sensing in fish. While often considered separately, these two processes are clearly intricately related because the gases that are transferred between the ventilatory water and blood at the gill are simultaneously sensed by chemoreceptors on, and within, the gill. Modulation of chemoreceptor discharge in response to changes in O(2) and CO(2) levels, in turn, is believed to initiate a series of coordinated cardiorespiratory reflexes aimed at optimising branchial gas transfer. The past decade has yielded numerous advances in terms of our understanding of gas transfer and gas sensing at the fish gill, particularly concerning the transfer and sensing of carbon dioxide. In addition, recent research has moved from striving to construct a single model that covers all fish species, to recognition of the considerable inter-specific variation that exists with respect to the mechanics of gas transfer and the cardiorespiratory responses of fish to changes in O(2) and CO(2) levels. The following review attempts to integrate gas transfer and gas sensing at the fish gill by exploring recent advances in these areas.
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Affiliation(s)
- Steve F Perry
- Department of Biology, University of Ottawa, Ottawa, Ontario, K1N 6N5 Canada.
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Claiborne JB, Edwards SL, Morrison-Shetlar AI. Acid-base regulation in fishes: cellular and molecular mechanisms. THE JOURNAL OF EXPERIMENTAL ZOOLOGY 2002; 293:302-19. [PMID: 12115903 DOI: 10.1002/jez.10125] [Citation(s) in RCA: 201] [Impact Index Per Article: 9.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
The mechanisms underlying acid-base transfers across the branchial epithelium of fishes have been studied for more than 70 years. These animals are able to compensate for changes to internal pH following a wide range of acid-base challenges, and the gill epithelium is the primary site of acid-base transfers to the water. This paper reviews recent molecular, immunohistochemical, and functional studies that have begun to define the protein transporters involved in the acid-base relevant ion transfers. Both Na(+)/H(+) exchange (NHE) and vacuolar-type H(+)-ATPase transport H(+) from the fish to the environment. While NHEs have been thought to carry out this function mainly in seawater-adapted animals, these proteins have now been localized to mitochondrial-rich cells in the gill epithelium of both fresh and saltwater-adapted fishes. NHEs have been found in the gill epithelium of elasmobranchs, teleosts, and an agnathan. In several species, apical isoforms (NHE2 and NHE3) appear to be up-regulated following acidosis. In freshwater teleosts, H(+)-ATPase drives H(+) excretion and is indirectly coupled to Na(+) uptake (via Na(+) channels). It has been localized to respiratory pavement cells and chloride cells of the gill epithelium. In the marine elasmobranch, both branchial NHE and H(+)-ATPase have been identified, suggesting that a combination of these mechanisms may be utilized by marine elasmobranchs for acid-base regulation. An apically located Cl(-)/HCO(3)(-) anion exchanger in chloride cells may be responsible for base excretion in fresh and seawater-adapted fishes. While only a few species have been examined to date, new molecular approaches applied to a wider range of fishes will continue to improve our understanding of the roles of the various gill membrane transport processes in acid-base balance.
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Affiliation(s)
- James B Claiborne
- Department of Biology, Georgia Southern University, Statesboro, Georgia 30460, USA.
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