Nucleated red cell function: metabolism and pH regulation

Boutilier, Robert G.; Ferguson, R. A.

doi:10.1139/z89-421

Cited by 59 publications

(11 citation statements)

References 41 publications

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“…Valet al (1994) showed that nucleotide triphosphate levels were increased in the erythrocytes of anemic fish. These increased levels of high energy phosphates may result in a decrease of pHi in fish red cells (Boutilier and Ferguson 1989).…”

Section: Plasma Catecholaminesmentioning

confidence: 99%

Blood gas parameters and the responses of erythrocytes in carp exposed to deep hypoxia and subsequent recovery

1996

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The quantitative importance of the adrenergic response of carp erythrocytes during severe oxygen restriction is not clear at present. Quantitative differences between in vivo and in vitro studies suggest that the response of carp erythrocytes may be dependent on the actual hypoxic condition. To our knowledge, a clear picture of the blood gas status, erythrocytic responses and catecholamines measured simultaneously in carp exposed to deep severe hypoxia or anoxia has not yet been reported. Therefore, we studied the physiological response of carp exposed to deep hypoxia at 0.3 kPa and subsequent recovery. Carp were fitted with an indwelling cannula in the dorsal aorta for repeated blood sampling and the blood was analysed for hematocrit, hemoglobin, mean cellular hemoglobin content, intra-and extracellular pH, pO2, pCO> total CO2 and catecholamines. Large fluctuations in arterial pO2 levels were observed in normoxic control carp, probably caused by the alternating breathing pattern of carp. Even at water pO2 levels of 0.3 kPa, arterial pO2 levels were maintained at about 0.2-0.3 kPa. Catecholamine levels were increased during deep hypoxia with noradrenaline as the predominant catecholamine. Hematological variables showed that the number of circulating erythrocytes was increased during hypoxia. The intracellular pH of carp red cells was maintained at pre-exposure values despite a considerable decrease of pHi. In this in vivo study, a marked decrease of the proton gradient across the red cell membrane (pHi-pHi), as high as 0.35 pH units, was observed, which is quantitatively similar to that usually observed in salmonids during hypoxia. It is suggested that the regulation of the carp erythrocytic pHi is probably caused to a major extent by deoxygenation of hemoglobin (Haldane effect) while adrenergic activa-

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Section: Plasma Catecholaminesmentioning

confidence: 99%

Blood gas parameters and the responses of erythrocytes in carp exposed to deep hypoxia and subsequent recovery

1996

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“…In recent years, research has focused intensively on two model systems, the teleost red blood cell (rbc) and the hepatocyte. The interaction of catecholamines with the rbc results in enhancement of blood oxygen transport (Nikinmaa and Tufts 1989;Boutilier and Ferguson 1989;Fievet and Motais 1991;Randall and Perry 1992; Thomas and Perry 1992) while the interaction of catecholamines with hepatocytes enhances the metabolic potential of the animal owing to mobilization of glucose (e.g. Ottolenghi et al 1985Ottolenghi et al , 1986Brighenti et al 1987b;Janssens and Lowrey 1987;Sheridan 1988;Mommsen et al 1988).…”

Section: Introductionmentioning

confidence: 99%

β-adrenergic signal transduction in fish: interactive effects of catecholamines and cortisol

Perry

Reid

1993

Fish Physiol Biochem

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The elevation of plasma catecholamine levels during acute stress initiates a series of compensatory physiological and biochemical mechanisms to alleviate the disruptive effects of stress on blood oxygen transport. Of particular importance is the β-adrenergic activation of a Na(+)/H(+) antiporter associated with the red blood cell (rbc) membrane. Upon activation, the Na(+)/H(+) antiporter extrudes H(+) from the rbc and the resultant alkalinization of the rbc interior serves to enhance both the affinity and the capacity of haemoglobin O2 binding. The activation of the Na(+)/H(+) exchanger is dependent upon the intracellular accumulation of cyclic AMP. The extent of cyclic AMP accumulation is determined, in part, by the number and/or affinities of cell surface β-adrenoreceptors. Recent studies have shown that the number of cell surface β-adrenoreceptors are rapidly increased during acute hypoxia and that this phenomenon may explain the enhanced responsiveness of hypoxic rbc's to exogenous catecholamines.In certain instances, plasma catecholamine and cortisol levels rise concurrently. We recently have shown that chronic (10 day) elevation of cortisol levels, in vivo, or short-term (24h) elevation, in vitro, caused significant elevation of internalized β-adrenoreceptors. Upon exposure of the rbc's to hypoxia, these additional receptors are rapidly recruited to the cell surface where they become functionally coupled to adenylate cyclase. Ultimately, therefore, chronic elevation of plasma cortisol levels increases the responsiveness of the rbc to circulating catecholamines. We recently have identified similar enhancement of cell surface β-adrenoreceptors by cortisol and increased physiological responsiveness (glycogenolysis) to catecholamines in trout hepatocytes.Thus, chronic elevation of cortisol levels appears to be generally adaptive for increasing the sensitivity of the β-adrenergic signal transduction system of at least two cell types (rbc's, hepatocytes) involved in the amelioration of acute stress when plasma catecholamine levels rise.

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“…Second, adrenergic stimulation of 2,4-DNP treated brown trout red cells did not cause changes in the chloride distribution ratio because intracellular alkalinization (and a consecutive increase in bicarbonate concentration) was prevented by the protonophore. Owing to the adrenergically stimulated sodium influx, the sodium pump is stimulated and the intracellular ATP concentration decreases (for example, see Boutilier and Ferguson 1989).…”

Section: Teleost Red Cells: Adrenergically Stimulated Sodiumproton Exmentioning

confidence: 99%

Regulation of acid and ion transfer across the membrane of nucleated erythrocytes

Nikinmaa¹,

Tufts²

1989

Can. J. Zool.

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NIKINMAA, M., and TUFTS, B. L. 1989. Regulation of acid and ion transfer across the membrane of nucleated erythrocytes.Can. J. Zool. 67: 3039-3045. The major pathways for proton transport across the membrane of nucleated erythrocytes are the passive Jacobs -Stewart cycle and the secondarily active sodium-proton exchange. The relative importance of these two pathways in the control of red cell pH depends on the sodium-proton exchange rate and the rate of the slowest step of passive proton equilibration. In cyclostome red cells, which lack anion exchange, intracellular pH is controlled by the sodium-dependent acid -extrusion mechanism. In unstimulated teleost red cells, the Jacobs-Stewart cycle appears to be the most important pathway for the transport of protons across the membrane. Adrenergic stimulation activates sodium-proton exchange. Sodium-proton exchange is able to increase intracellular pH and decrease extracellular pH because the rate of proton transport via the Jacobs -Stewart cycle is limited by the uncatalysed extracellular dehydration of carbonic acid to carbon dioxide. The turnover rate of the adrenergically activated sodium-proton exchange is influenced by pH and oxygen tension. In amphibian red cells, acidification activates sodium-proton exchange. The exchange may limit the changes in intracellular pH after acid-base disturbances.NIKINMAA, M., et TUFTS, B. L. 1989. Regulation of acid and ion transfer across the membrane of nucleated erythrocytes.Can. J. Zool. 67 : 3039 -3045. Les principales voies de transport des protons B travers la membrane des krythrocytes nuclkQ sont la voie passive du cycle Jacobs -Stewart et la voie active secondaire des kchanges sodium-protons. L'importance relative de ces deux voies dans le contrdle du pH des krythrocytes dkpend du taux des kchanges sodium-protons et de la vitesse de l'ktape la plus lente d'ktablissement passif de l'kquilibre des protons. Dans les krythrocytes des cyclostomes, oii il ne se fait pas d'kchange d'anions, le pH intracellulaire est contrdlk par un mkcanisme d'expulsion des acides sous contrdle du sodium. Dans les krythrocytes non stimulks des tklkostkens, le cycle Jacobs -Stewart semble la voie la plus importante de transport des protons B travers la membrane. La stimulation adrknergique active les kchanges sodium-protons. Les kchanges sodium-protons peuvent augmenter le pH intracellulaire et diminuer le pH extracellulaire parce que la vitesse de transport des protons par le cycle Jacobs -Stewart est limitke par la dkshydratation extracellulaire non catalyde de l'acide carbonique qui se transforme en gaz carbonique. Le taux de remplacement des kchanges sodium-protons sous contrdle adrknergique est influence par le pH et la tension d'oxygkne. Dans les krythrocytes des amphibiens, l'acidification active les kchanges sodium-protons. Ces kchanges peuvent limiter les modulations du pH intracellulaire aprks des perturbations de l'kquilibre acide -base.[Traduit par la revue]

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Nucleated red cell function: metabolism and pH regulation

Cited by 59 publications

References 41 publications

Blood gas parameters and the responses of erythrocytes in carp exposed to deep hypoxia and subsequent recovery

Blood gas parameters and the responses of erythrocytes in carp exposed to deep hypoxia and subsequent recovery

β-adrenergic signal transduction in fish: interactive effects of catecholamines and cortisol

Regulation of acid and ion transfer across the membrane of nucleated erythrocytes

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