scholarly journals Influence of Haemoglobin Conformation, Nitrite and Eicosanoids on K+ Transport Across the Carp Red Blood Cell Membrane

1992 ◽  
Vol 171 (1) ◽  
pp. 349-371 ◽  
Author(s):  
FRANK B. JENSEN
Keyword(s):  
Membrane Potential ◽  
Blood Cell ◽  
Red Blood Cell ◽  
Quaternary Structure ◽  
Large Fraction ◽  
Nordihydroguaiaretic Acid ◽  
K Uptake ◽  
Root Effect ◽  
T State ◽  
K Transport

The regulation of K+ transport across the red blood cell (RBC) membrane by haemoglobin (Hb) conformation was studied in carp, and the K+ transport mechanisms were identified. When a large proportion of Hb in the R quaternary structure was secured by oxygenation of blood at pH8.14, a net RBC K+ efflux was induced, which was accompanied by RBC shrinkage. This K+ efflux was resistant to ouabain and inhibited by furosemide and DIDS and by substitution of NO3− for Cl−, showing it to result from a K+/Cl− cotransport mechanism. Deoxygenation of the RBCs (Hb in T structure) eliminated the Cl−-dependent K+ efflux and resulted in a net K+ uptake via the Na+/K+ pump. These changes were fully reversible. Nitrite-induced methaemoglobin formation in deoxygenated blood, which converts a large fraction of the T structure Hb into an R-like conformation, shifted the K+ uptake to a Cl−-dependent K+ efflux similar to that seen in oxygenated cells. When the allosteric equilibrium between the R and T structures of Hb was gradually shifted towards the T state by decreases in pH, the Cl−-dependent K+ efflux from oxygenated cells decreased. At pH7.52, where the Root effect caused a potent stabilisation of the T state, the K+ efflux was reversed to a net K+ uptake. A similar change was induced in methaemoglobin-containing deoxygenated blood, since low pH also favours a T-like conformation of metHb. The variable K+ fluxes could not be related to changes in membrane potential or pH but were always directly related to the experimental modulation of the relative proportions of R- and T-structure Hb. It is proposed that Hb conformation governs K+ movements via a different binding of T and R structures to integral membrane proteins, and that a large fraction of R-structure Hb triggers the Cl−dependent K+ efflux mechanism. Application of inhibitors and a substrate of prostaglandin and leukotriene synthesis did not influence the K+ efflux from oxygenated erythrocytes. However, a fraction of the K+ efflux from nitrite-treated deoxygenated cells was inhibited by nordihydroguaiaretic acid, suggesting that a slightly larger K+ efflux from these RBCs than from oxygenated RBCs was related to leukotriene production caused by nitrite entry. A much larger influx of nitrite to deoxygenated than to oxygenated RBCs was positively correlated with the distribution ratio of H+ and the membrane potential, supporting the view that nitrite primarily enters the cells via conductive transport. The physiological implications of the results are discussed.

scholarly journals Red blood cell carbonic anhydrase mediates oxygen delivery via the Root effect in red drum

2020 ◽  
Vol 223 (22) ◽  
pp. jeb232991
Author(s):  
Angelina M. Dichiera ◽  
Andrew J. Esbaugh
Keyword(s):  
Carbonic Anhydrase ◽  
Blood Cell ◽  
Red Blood Cell ◽  
Fold Increase ◽  
Red Drum ◽  
Sciaenops Ocellatus ◽  
Scaling Exponent ◽  
Root Effect ◽  
Tightly Coupled

ABSTRACTOxygen (O2) and carbon dioxide (CO2) transport are tightly coupled in many fishes as a result of the presence of Root effect hemoglobins (Hb), whereby reduced pH reduces O2 binding even at high O2 tensions. Red blood cell carbonic anhydrase (RBC CA) activity limits the rate of intracellular acidification, yet its role in O2 delivery has been downplayed. We developed an in vitro assay to manipulate RBC CA activity while measuring Hb-O2 offloading following a physiologically relevant CO2-induced acidification. RBC CA activity in red drum (Sciaenops ocellatus) was inhibited with ethoxzolamide by 53.7±0.5%, which prompted a significant reduction in O2 offloading rate by 54.3±5.4% (P=0.0206, two-tailed paired t-test; n=7). Conversely, a 2.03-fold increase in RBC CA activity prompted a 2.14-fold increase in O2 offloading rate (P<0.001, two-tailed paired t-test; n=8). This approximately 1:1 relationship between RBC CA activity and Hb-O2 offloading rate coincided with a similar allometric scaling exponent for RBC CA activity and maximum metabolic rate. Together, our data suggest that RBC CA is rate limiting for O2 delivery in red drum.

scholarly journals Effects of negatively charged shift reagents on red blood cell morphology, lithium ion transport, and membrane potential

1990 ◽  
Vol 29 (20) ◽  
pp. 3979-3985 ◽  
Author(s):  
Ravichandran Ramasamy ◽  
Duarte Mota de Freitas ◽  
Warren Jones ◽  
Frederick Wezeman ◽  
Richard Labotka ◽  
...  
Keyword(s):  
Membrane Potential ◽  
Blood Cell ◽  
Ion Transport ◽  
Cell Morphology ◽  
Red Blood Cell ◽  
Lithium Ion ◽  
Blood Cell Morphology ◽  
Shift Reagents

scholarly journals The role of potassium transport in the generation of a pH gradient in Escherichia coli

1981 ◽  
Vol 198 (3) ◽  
pp. 691-698 ◽  
Author(s):  
R G Kroll ◽  
I R Booth
Keyword(s):  
Escherichia Coli ◽  
Membrane Potential ◽  
Respiratory Rate ◽  
Potassium Transport ◽  
Ph Gradient ◽  
Simple Relationship ◽  
K Uptake ◽  
Net Uptake ◽  
K Transport

The role of K+ transport in the generation of a pH gradient in Escherichia coli has been investigated. In K+-depleted cells, net K+ uptake dissipated delta psi (membrane potential) and led to an increase in delta pH (pH gradient). The magnitude of the delta pH formed bore a simple relationship to the net K+ uptake and was substantially independent of the respiratory rate. In K+-replete cells, generation of a pH gradient was again K+-dependent, although no net uptake of this cation occurred. The results are discussed in terms of K+ cycling, and it is suggested that delta pH is in part a function of the rate of cycling and independent of the respiratory rate.

The effect of oxidizing agents and diabetes mellitus on the human red blood cell membrane potential

1996 ◽  
Vol 29 (3) ◽  
pp. 283-286 ◽  
Author(s):  
Katarzyna Augustyniak ◽  
Ilya Zavodnik ◽  
Danuta Palecz ◽  
Konrad Szosland ◽  
Maria Bryszewska
Keyword(s):  
Diabetes Mellitus ◽  
Membrane Potential ◽  
Cell Membrane ◽  
Blood Cell ◽  
Red Blood Cell ◽  
Cell Membrane Potential ◽  
Oxidizing Agents ◽  
Red Blood Cell Membrane

The evolution of novel hemoglobin functions and physiological innovation

Hemoglobin ◽  
2018 ◽  
pp. 152-175
Author(s):  
Jay F. Storz
Keyword(s):  
Blood Cell ◽  
Case Studies ◽  
Red Blood Cell ◽  
Adaptive Radiation ◽  
Respiratory Function ◽  
Teleost Fishes ◽  
Root Effect ◽  
Allosteric Properties

Chapter 7 explores the evolution of novel hemoglobin functions and physiological innovations. In the epic sweep of life’s history on Earth, globin proteins such as vertebrate hemoglobin were only recently co-opted for a respiratory function in circulatory O2 transport. Even after blood-O2 transport became an entrenched feature of vertebrate physiology, red blood cell hemoglobins evolved additional specializations of function in particular lineages. In some cases, like the Root effect of fish hemoglobins, these new functions represent key physiological innovations that have contributed to adaptive radiation. This chapter explores several case studies of how the evolution of novel allosteric properties have enhanced and expanded the physiological capacities of particular vertebrate groups, with an emphasis on teleost fishes and crocodilians.

Impaired Mitophagy of Erythrocytes Leads to Anemia in Patients with Myelodysplastic Syndromes

Blood ◽  
2016 ◽  
Vol 128 (22) ◽  
pp. 5507-5507
Author(s):  
Liyan Yang ◽  
Huaquan Wang ◽  
Zonghong Shao
Keyword(s):  
Membrane Potential ◽  
High Risk ◽  
Blood Cell ◽  
Mitochondrial Membrane Potential ◽  
Red Blood Cell ◽  
Mitochondrial Membrane ◽  
Low Risk ◽  
Significant Difference ◽  
Normal Controls ◽  
Nucleated Red Blood Cell

Abstract Objective: To investigate the change of mitophagy level of bone marrow nucleated red blood cell in anemia patients with myelodysplastic syndromes (MDS), to explore its significance in the anemic pathogenesis of MDS. Methods: Fifty anemia patients with MDS and twenty-six normal controls were enrolled in this study. The mitophagy were observed by transmission electron microscopy (TEM). The level of autophagy-associated protein LC3B, the number of mitochondria, mitochondrial membrane potential, the level of ROS in GlycoA + nucleated red blood cell were measured by Flow cytometry .The expression of AMPK, ULK1, mTOR mRNA of GlycoA + nucleated red blood cell were measured by real time PCR. The expression of the mitochondrial outer membrane protein TOM20 in GlycoA + nucleated red blood cell were detected by Western blotting. Results: (1) Autophagosome or autolysosome including mitochondria were scarcely observed by TEM. (2) The expression of LC3B in GlycoA + nucleated red blood cell in high-risk MDS patients(0.22±0.12) was significantly lower than that in normal controls (0.43±0.22, P<0.01), and lower than that in low-risk MDS patients (0.40±0.16, P<0.01), there were no significant difference in expression of LC3B between normal controls and low-risk MDS patients (P>0.05); (3) The number of mitochondria in GlycoA + nucleated red blood cell in high-risk MDS patients (937.17±707.85) was significantly higher than that in normal controls (513.49±372.33, P<0.05), and higher than that in low-risk MDS patients (461.74±438.02, P<0.01), there were no significant difference in number of mitochondria between normal controls and low-risk MDS patients (P>0.05); (4) The level of mitochondrial membrane potential in GlycoA + nucleated red blood cell in high-risk MDS patients(4.24±3.00)was significantly higher than that in normal controls (2.04±1.11, P<0.01), and higher than that in low-risk MDS patients (2.11±1.10, P<0.01), there were no significant difference in the level of mitochondrial membrane potential between normal controls and low-risk MDS patients(P>0.05); (5) The level of ROS in GlycoA + nucleated red blood cell in high-risk MDS patients(438.65±322.83)was significantly higher than that in normal controls (242.77±136.87, P<0.01), and higher than that in low-risk MDS patients(197.40+95.07, P<0.01), there were no significant difference in the level of ROS between normal controls and low-risk MDS patients(P>0.05); (6) The expression of AMPK mRNA in GlycoA + nucleated red blood cell in high-risk MDS patients(1.06±1.51) was significantly lower than that in low-risk MDS patients (4.35±4.79, P>0.05), there were no significant difference with normal controls(P>0.05). (7) The exception of ULK1 mRNA in GlycoA + nucleated red blood cell in high-risk MDS patients (0.64±0.91) was significantly lower than that in normal controls (2.70±3.27, P<0.01), and lower than that in low-risk MDS patients(4.82±4.81, P<0.01);(8)The level of mTOR mRNA in GlycoA + nucleated red blood cell in high-risk MDS patients (2.81±2.80) was significantly higher than that in normal controls (1.28±0.81, P<0.05),and higher than that in low-risk MDS patients (0.85±0.74, P<0.05), there were no significant difference in expression of AMPK,ULK1and mTOR mRNA between low-risk MDS patients and normal controls (P>0.05). (9) The expression of mitochondrial outer membrane protein TOM20 in high-risk MDS patients was higher than that in normal controls. Conclusion: The pathogenesis of anemia in MDS may be correlated with declining mitophagy level, increasing damaged mitochondria, increasing ROS, DNA damage, and shortening the life of nucleated red blood cells, it may be an effective method to induce mitophagy to correct anemia in MDS. Disclosures No relevant conflicts of interest to declare.

DETERMINATION OF SPONTANEOUS CURVATURE AND INTERNAL PRESSURE OF VESICLES AND RED CELLS BY THEIR SHAPE AND THE FLEXOELECTRIC EFFECT OF MEMBRANE

1992 ◽  
Vol 06 (25) ◽  
pp. 1577-1582 ◽  
Author(s):  
OU-YANG ZHONG-CAN ◽  
HU JIAN-GUO ◽  
LIU JI-XING
Keyword(s):  
Membrane Potential ◽  
Liquid Crystals ◽  
Blood Cell ◽  
Internal Pressure ◽  
Red Blood Cell ◽  
Spontaneous Curvature ◽  
Flexoelectric Effect ◽  
Vesicle Shape ◽  
Good Agreement

Three geometric relations for vesicle equilibrium within the Helfrich elasticity model have been derived. The relations can serve to determine the spontaneous curvature c0 and cell internal pressure −Δp=pin−pext from the vesicle shape. In analogy with the theory of the flexoelectric effect of nematic liquid crystals we have also obtained a relation between c0 and the membrane potential. By applying these predictions to the human red blood cell (RBC) shape measured by Evans and Fung we found good agreement of the calculated potential with measured values previously given by other biologists by direct impaling RBC with a microelectrode. The calculated value of the internal pressure is discussed by comparison with previous works.

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