Adrenergic Control of Red Cell pH, Organic Phosphate Concentrations and Haemoglobin Function in Teleost Fish

Nikinmaa, Mikko; Boutilier, Robert G.

doi:10.1007/978-3-642-79666-1_5

Cited by 16 publications

(7 citation statements)

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“…An obvious exception is the unique βNHE of rainbow trout red blood cells (Borgese et al, 1992), which was extensively characterized using pharmacological and molecular techniques (Nikinmaa and Boutilier, 1995;Malapert et al, 1997).…”

Section: Discussionmentioning

confidence: 99%

Branchial expression and localization of SLC9A2 and SLC9A3 sodium/hydrogen exchangers and their possible role in acid–base regulation in freshwater rainbow trout (Oncorhynchus mykiss)

Ivanis

Esbaugh

Perry

2008

Journal of Experimental Biology

118

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SUMMARY-uptake and base excretion. Levels of mRNA for NHE2, the predominant isoform in the gill, were increased during 72 h of hypercapnic acidosis; NHE3 mRNA and protein levels were unaffected. Because plasma cortisol levels were increased during hypercapnia (from 35.3±9.4 to 100.1±30.9 ng ml -1 ), the effects of experimentally elevated cortisol levels on NHE expression were investigated. The elevation of plasma cortisol using intraperitoneal implants caused a significant increase in NHE2 mRNA expression without affecting NHE3 mRNA or protein abundance. Thus, we suggest that NHE2 contributes to acid-base regulation during hypercapnia owing to its transcriptional regulation by cortisol. The finding of NHE expression in PNA + MRCs is discussed with reference to current models of ionic and acid-base regulation in teleost fish.

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Section: Discussionmentioning

confidence: 99%

Branchial expression and localization of SLC9A2 and SLC9A3 sodium/hydrogen exchangers and their possible role in acid–base regulation in freshwater rainbow trout (Oncorhynchus mykiss)

Ivanis

Esbaugh

Perry

2008

Journal of Experimental Biology

118

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“…Hb-O 2 affinity (P 50 ), Root effect and cooperativity (Hill coefficient, n H ) were automatically calculated from the saturation curves by a manufacturer-supplied spreadsheet. The blood sampling method used may have overestimated Hb-O 2 affinity by causing the release of catecholamines, which activate NHE, increase red blood cell pH and ultimately reduce P 50 (Nikinmaa and Boutilier, 1995;Reid et al, 1998). Blood was collected as quickly as possible to minimize the effects of a catecholaminergic response, but because of the small size of K. marmoratus, this was the only practical method of collecting blood.…”

Section: Blood Analysismentioning

confidence: 99%

The amphibious fishKryptolebias marmoratususes alternate strategies to maintain oxygen delivery during aquatic hypoxia and air exposure

Turko

Robertson

Bianchini

et al. 2014

Journal of Experimental Biology

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Despite the abundance of oxygen in atmospheric air relative to water, the initial loss of respiratory surface area and accumulation of carbon dioxide in the blood of amphibious fishes during emersion may result in hypoxemia. Given that the ability to respond to low oxygen conditions predates the vertebrate invasion of land, we hypothesized that amphibious fishes maintain O 2 uptake and transport while emersed by mounting a co-opted hypoxia response. We acclimated the amphibious fish Kryptolebias marmoratus, which are able to remain active for weeks in both air and water, for 7 days to normoxic brackish water (15‰, ~21 kPa O 2 ; control), aquatic hypoxia (~3.6 kPa), normoxic air (~21 kPa) or aerial hypoxia (~13.6 kPa). Angiogenesis in the skin and bucco-opercular chamber was pronounced in air-versus water-acclimated fish, but not in response to hypoxia. Aquatic hypoxia increased the O 2 -carrying capacity of blood via a large (40%) increase in red blood cell density and a small increase in the affinity of hemoglobin for O 2 (P 50 decreased 11%). In contrast, air exposure increased the hemoglobin O 2 affinity (decreased P 50 ) by 25% without affecting the number of red blood cells. Acclimation to aerial hypoxia both increased the O 2 -carrying capacity and decreased the hemoglobin O 2 affinity . These results suggest that O 2 transport is regulated both by O 2 availability and also, independently, by air exposure. The ability of the hematological system to respond to air exposure independent of O 2 availability may allow extant amphibious fishes, and may also have allowed primitive tetrapods to cope with the complex challenges of aerial respiration during the invasion of land.KEY WORDS: Hemoglobin, Oxygen-carrying capacity, Hemoglobin-oxygen affinity, Air-breathing organ, Air-breathing fish, Mangrove rivulus INTRODUCTIONThe transition from aquatic to terrestrial life represents a major step in vertebrate evolution because the physical conditions between these environments are dramatically different. Oxygen solubility is relatively low in water and even well-oxygenated aquatic environments contain only about 3% of the O 2 available in atmospheric air (Dejours, 1988). Low concentrations of aquatic O 2 , particularly in hypoxic habitats, have often been hypothesized to be one of the driving forces behind the evolution of amphibious or terrestrial life histories because invasion of land would allow animals to exploit the O 2 -rich aerial environment (Graham, 1997). RESEARCH ARTICLEDepartment of Integrative Biology, University of Guelph, Guelph, ON N1G 2W1, Canada.*Author for correspondence (aturko@uoguelph.ca) Received 4 July 2014; Accepted 15 September 2014Taking advantage of aerial O 2 presents several challenges for fishes. Water-breathing fishes exchange respiratory gases across the gills but during emersion the gill lamellae typically collapse and coalesce, reducing the surface area available for respiration. Accumulation of CO 2 in the blood of emersed fishes, resulting from the low solubility of CO 2 in...

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“…Motais and colleagues [31] have proposed that this Clindependent route may still represent transport via the KCC1, but with an altered pattern of anion dependence that is induced by hypotonic swelling. On the other hand, trout erythrocytes can show activation of K flux without hypotonic shock, by the adrenergic activation of the Na/H exchanger [5,34], by oxygenation [7,33], or by treatment with ammonium salts [31] and it is under all these conditions that K efflux is strictly Cl-dependent. There are also differences in the O 2 sensitivity of the various components of K fluxes involved in RVD [33], again pointing to different systems being present.…”

Section: Introductionmentioning

confidence: 97%

The relationship between hypotonically-induced taurine and K fluxes in trout red blood cells

Kiessling

Ellory

Cossins

2000

Pflugers Arch - Eur J Physiol

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Hypotonic swelling of teleost erythrocytes activates multiple transport systems leading to the regulatory decrease of cell volume. We have examined using pharmacological manipulation the swelling-induced taurine flux pathway in red blood cells of the rainbow trout and its relationship to swelling-induced K flux pathways. We show that the activation and deactivation of taurine flux is rapid and that the flux is a sigmoidal function of cell volume. N-ethylmaleimide (NEM) and the non-specific protein kinase inhibitor, staurosporine, both inactivated the hypotonically-induced taurine flux with concentrations eliciting half-maximal inhibition (IC50s) of 212 and 17 micromol(-1), respectively. The low taurine fluxes under isotonic conditions were unaffected. By contrast, the tyrosine kinase inhibitor, genistein, partially inhibited taurine flux under both isotonic and hypotonic conditions. The specific phosphatase inhibitor, calyculin A, had no inhibitory or stimulatory effect under either condition whilst the less-specific phosphatase inhibitor, ortho-vanadate, reduced taurine flux only under hypotonic conditions. In these respects the regulatory control of the taurine pathway differs from the Cl-dependent K flux. However, NEM and staurosporine also inhibited the Cl-independent K flux, both with similar IC50s to those observed for taurine fluxes. This supports the idea of the hypotonically-induced taurine flux and the Cl-independent K flux sharing the same transport pathway.

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Adrenergic Control of Red Cell pH, Organic Phosphate Concentrations and Haemoglobin Function in Teleost Fish

Cited by 16 publications

References 100 publications

Branchial expression and localization of SLC9A2 and SLC9A3 sodium/hydrogen exchangers and their possible role in acid–base regulation in freshwater rainbow trout (Oncorhynchus mykiss)

Branchial expression and localization of SLC9A2 and SLC9A3 sodium/hydrogen exchangers and their possible role in acid–base regulation in freshwater rainbow trout (Oncorhynchus mykiss)

The amphibious fishKryptolebias marmoratususes alternate strategies to maintain oxygen delivery during aquatic hypoxia and air exposure

The relationship between hypotonically-induced taurine and K fluxes in trout red blood cells

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