Oxygenation-activated K fluxes in trout red blood cells

The effect of oxygenation on the dissipative fluxes of K in trout red blood cells has been determined. Unidirectional influx under low oxygen tension (PO2 = 1 kPa) was 0.56 +/- 0.07 mmol.l-1 packed cells.h-1. Within a few minutes of equilibration with high oxygen tension (PO2 = 120 kPa), influx was increased 14-fold, and this was associated with a progressive loss of KCl and a cell shrinkage. K influx progressively declined over the following 3 h to levels close to those characteristic of cells at low oxygen tension. Replacement of medium Cl by NO3- or methane sulfonate inhibited the stimulation due to high oxygen as did furosemide and low extracellular pH. The oxygenation-stimulated influx was highly volume sensitive, being increased by up to 100% by osmotic swelling and decreased by osmotic shrinkage. By contrast, the small influx under low oxygen tension was unaffected by either Cl replacement or by shrinkage and increased only with extreme swelling. Thus high oxygen tension activated a Cl-dependent and furosemide-sensitive K flux. Once activated, the mechanism was rapidly deactivated on transfer back to low oxygen tension but slowly deactivated when maintained at high PO2. The oxygenation-stimulated flux mechanism promotes a rapid and more complete volume regulatory decrease than in cells at low oxygen tension.

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Inhibition of Rho Kinase by Y27632 Increases Low Oxygen Tension‐Induced ATP Release from Human Red Blood Cells (RBCs)

The FASEB Journal ◽

10.1096/fasebj.24.1_supplement.974.3 ◽

2010 ◽

Vol 24 (S1) ◽

Author(s):

Kelly Thuet ◽

Elizabeth Bowles ◽

Meera Sridharan ◽

Shaquria Adderley ◽

Randy Sprague ◽

...

Keyword(s):

Red Blood Cells ◽

Oxygen Tension ◽

Blood Cells ◽

Atp Release ◽

Rho Kinase ◽

Low Oxygen ◽

Human Red Blood Cells ◽

Low Oxygen Tension

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Pannexin 1 (PANX1) is a Conduit for ATP Released from Human Red Blood Cells (RBCs) Exposed to Low Oxygen Tension

The FASEB Journal ◽

10.1096/fasebj.24.1_supplement.777.6 ◽

2010 ◽

Vol 24 (S1) ◽

Author(s):

Meera Sridharan ◽

Shaquria Adderley ◽

Elizabeth Bowles ◽

Alan Stephenson ◽

Mary Ellsworth ◽

...

Keyword(s):

Red Blood Cells ◽

Oxygen Tension ◽

Blood Cells ◽

Low Oxygen ◽

Pannexin 1 ◽

Human Red Blood Cells ◽

Low Oxygen Tension

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Comparison of buffer and red blood cell perfusion of guinea pig heart oxygenation

AJP Heart and Circulatory Physiology ◽

10.1152/ajpheart.00383.2003 ◽

2003 ◽

Vol 285 (5) ◽

pp. H1819-H1825 ◽

Cited By ~ 32

Author(s):

Kenneth A. Schenkman ◽

Daniel A. Beard ◽

Wayne A. Ciesielski ◽

Eric O. Feigl

Keyword(s):

Oxygen Consumption ◽

Guinea Pig ◽

Oxygen Saturation ◽

Red Blood Cells ◽

Ventricular Function ◽

Oxygen Tension ◽

Blood Cells ◽

Low Oxygen ◽

Guinea Pig Heart ◽

Perfused Hearts

Myocardial mean myoglobin oxygen saturation was determined spectroscopically from isolated guinea pig hearts perfused with red blood cells during increasing hypoxia. These experiments were undertaken to compare intracellular myoglobin oxygen saturation in isolated hearts perfused with a modest concentration of red blood cells (5% hematocrit) with intracellular myoglobin saturation previously reported from traditional buffer-perfused hearts. Studies were performed at 37°C with hearts paced at 240 beats/min and a constant perfusion pressure of 80 cmH2O. It was found that during perfusion with a hematocrit of 5%, baseline mean myoglobin saturation was 93% compared with 72% during buffer perfusion. Mean myoglobin saturation, ventricular function, and oxygen consumption remained fairly constant for arterial perfusate oxygen tensions above 100 mmHg and then decreased precipitously below 100 mmHg. In contrast, mean myoglobin saturation, ventricular function, and oxygen consumption began to decrease even at high oxygen tension with buffer perfusion. The present results demonstrate that perfusion with 5% red blood cells in the perfusate increases the baseline mean myoglobin saturation and better preserves cardiac function at low oxygen tension relative to buffer perfusion. These results suggest that caution should be used in extrapolating intracellular oxygen dynamics from buffer-perfused to blood-perfused hearts.

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Volume regulation by Amphiuma red blood cells: cytosolic free Ca and alkali metal-H exchange

AJP Cell Physiology ◽

10.1152/ajpcell.1986.250.3.c423 ◽

1986 ◽

Vol 250 (3) ◽

pp. C423-C429 ◽

Cited By ~ 40

Author(s):

P. M. Cala ◽

L. J. Mandel ◽

E. Murphy

Keyword(s):

Alkali Metal ◽

Red Blood Cells ◽

Blood Cells ◽

Volume Regulation ◽

Null Point ◽

Cell Swelling ◽

Maximal Concentration ◽

Cell Shrinkage ◽

Osmotic Swelling ◽

Intracellular Ca

Osmotic swelling of Amphiuma red blood cells results in activation of electroneutral K-H exchange, whereas cell shrinkage activates an electroneutral Na-H exchange. These K-H and Na-H exchangers function to restore cell volume to normal after cell swelling and shrinkage, respectively. Our previous studies have suggested that Ca plays a role in volume-dependent activation of K-H exchange. In the present studies, intracellular free Ca levels were measured employing the Ca-sensitive extracellular dye arsenazo III and a previously described null-point method. Control values for intracellular free Ca averaged 0.46 +/- 0.15 microM. Cell shrinkage caused this value to decrease to 0.16 +/- 0.11 microM, whereas either cell swelling or addition of 5 microM A23187 resulted in saturation of intracellular Ca buffers, suggesting that both treatments caused an increase in intracellular free Ca. In the presence of 7 microM A23187, the rate of K-H exchange displayed a hyperbolic relationship as a function of extracellular Ca (Cao). The apparent half-maximal concentration for Cao (in the presence of 7 microM A23187) was 0.27 mM for osmotically swollen cells and 1.9 mM for cells in isotonic medium, suggesting that the Ca affinity of a modulating site is increased in swollen cells. Inhibitors of Ca-mediated processes, such as quinidine and the phenothiazines, inhibited K-H exchange. In contrast, the phenothiazines chlorpromazine and trifluoperazine stimulated Na-H exchange by osmotically shrunken cells. These results suggest that increases in intracellular free Ca are involved in stimulating K-H exchange while repressing Na-H exchange in Amphiuma red blood cells.

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Cellular and molecular alterations of buffalo oocytes cultured under two different levels of oxygen tension during in vitro maturation

Zygote ◽

10.1017/s0967199420000945 ◽

2021 ◽

pp. 1-11

Author(s):

Nasser Ghanem ◽

Dalia Abd-El Rahman Ahmed ◽

Sherif Mohamed Dessouki ◽

Marwa Said Faheem ◽

Ahmed Yehia Gad ◽

...

Keyword(s):

Oxygen Tension ◽

High Oxygen ◽

Mitochondrial Activity ◽

Low Oxygen ◽

Cortical Granules ◽

Molecular Changes ◽

Oxygen Levels ◽

Nuclear Maturation ◽

Meiotic Progression ◽

Low Oxygen Tension

Summary This study was conducted to monitor the cellular and molecular changes of buffalo cumulus–oocytes complexes (COCs) cultured under high or low oxygen levels. Morphologically good quality COCs (n = 1627) were screened using brilliant cresyl blue (BCB) staining and placed into three groups (BCB+, BCB− and control). All groups of COCs were cultured under low (5%) or high (20%) oxygen tensions. Intracellular and molecular changes including oocyte ultrastructure, lipid contents, mitochondrial activity and transcript abundance of genes regulating different pathways were analyzed in the matured oocyte groups. The results revealed that oxygen tension did not affect cumulus expansion rates, however the BCB+ group had a higher (P ≤ 0.05) expansion rate compared with the BCB− group. BCB− oocytes recorded the lowest meiotic progression rate (P ≤ 0.05) under high oxygen levels that was linked with an increased level of reactive oxygen species (ROS) compared with the BCB+ oocytes. Ultrastructure examination indicated that BCB+ oocytes had a higher rate of cortical granules migration compared with BCB− under low oxygen tension. In parallel, our results indicated the upregulation of NFE2L2 in groups of oocytes cultured under high oxygen tension that was coupled with reduced mitochondrial activity. In contrast, the expression levels of MAPK14 and CPT2 genes were increased (P ≤ 0.05) in groups of oocytes cultured under low compared with high oxygen tension that was subsequently associated with increased mitochondrial activity. In conclusion, data from the present investigation indicated that low oxygen tension is a favourable condition for maintaining the mitochondrial activity required for nuclear maturation of buffalo oocytes. However, low-quality oocytes (BCB−) responded negatively to high oxygen tension by reducing the expression of gene-regulating metabolic activity (CPT2). This action was an attempt by BCB− oocytes to reduce the increased levels of endogenously produced ROS that was coupled with decreased expression of the gene controlling meiotic progression (MAPK14) in addition to nuclear maturation rate.

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