Chang Gung University Department of Medical Biotechnology Clinical Hematology

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Chang Gung UniversityDepartment of Medical
Biotechnology Clinical Hematology
Biology of the Red Cell IV V? Membrane and
other cytoplasmic components
Dr. Chiu Spring, 2012
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Lecture Outline

• I. The red cell membrane structure
• A. Membrane structural components?
• Lipids, proteins and carbohydrates
• B. The bilayer coupling hypothesis
• C. Asymmetry of membrane phospholipids
• II. Functions of the red cell membrane
• A. Maintenance of cell volume
• 1. Na and K content
• 2. Osmotic fragility
• B. Ca2 Homeostasis
• C. Anion exchange

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Lecture Outline

• V. Required reading
• Text (Essential Haematology) pp 18-20.
• VI. References
• 1. Rifkind r, et al Fundamentals of
  Hematology, pp55-56,71-73,
• 1986
• 2. Lux, S. and S. Shohet. The
  erythrocyte membrane skeleton.
• Hospital Practice pp 77-83, Oct.
  1984
• 3. Lubin B, Kuypers F, Chiu D. Red cell
  membrane lipid
• dynamices in The Red Cell. Alan R.
  Liss, Inc. 1989 pp507-524
• 4. Beutler, E. Red cell metabolism A
  manual of biochemical
• methods. Crune and Stratton, 1984
• 5. Chiu, DTY, Liu TZ. Free radical and
  oxidative damage in human
• blood cells. J Biomed. Sci 4
  256-259, 1997.

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Lecture Outline

• I. The red cell membrane structure
• A. Membrane structural components?
• Lipids, proteins and carbohydrates
• B. The bilayer coupling hypothesis
• C. Asymmetry of membrane phospholipids
• II. Functions of the red cell membrane
• A. Maintenance of cell volume
• 1. Na and K content
• 2. Osmotic fragility
• B. Ca2 Homeostasis
• C. Anion exchange

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The red cell membrane structure
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Biological Membranes as Bilayer Couples. A
Molecular Mechanism ofDrug-Erythrocyte
Interactions
Sheetz MP, Singer SJ. Proc Natl Acad Sci U S A.
1974 Nov71(11)4457-61.
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ABSTRACT We propose that membranes whose
proteins and polar lipids are distributed
asymmetrically in the two halves of the membrane
bilayer can act as bilayer couples, i.e., the two
halves can respond differently to a perturbation.
This hypothesis is applied to the interactions of
amphipathic drugs with human erythrocytes. It is
proposed that anionic drugs intercalate mainly
into the lipid in the exterior half of the
bilayer, expand that layer relative to the
cytoplasmic half, and thereby induce the cell to
crenate, while permeable cationic drugs do the
opposite and cause the cell to form cup-shapes.
This differential distribution of the drugs is
attributed to interactions with the
phosphatidylserine that is concentrated in the
cytoplasmic half of the membrane. Impermeable
amphipathic drugs intercalate only into the
exterior half of the bilayer, and therefore are
crenators of the intact cell. Several predictions
of this hypothesis have been confirmed
experimentally with erythrocytes and erythrocyte
ghosts. The bilayer couple hypothesis may
contribute to the explanation of many
membrane-mediated phenomena in cell biology.
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Membrane bilayer coupling with changing RBC
morphology
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A schematic representation of the red cell
membrane structure
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C. Asymmetry of membrane
phospholipids
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Lecture Outline

• I. The red cell membrane structure
• A. Membrane structural components?
• Lipids, proteins and carbohydrates
• B. The bilayer coupling hypothesis
• C. Asymmetry of membrane phospholipids
• II. Functions of the red cell membrane
• A. Maintenance of cell volume
• 1. Na and K content
• 2. Osmotic fragility
• B. Ca2 Homeostasis
• C. Anion exchange

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Osmotic fragility
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Lecture Outline

• III. Red cell deformability ( A brief review )
• A. Factors affecting red cell deformability
• 1. Cytoplasmic viscosity
• 2. intracellular rubbish
• 3. membrane rigidity
• 4. surface to volume ratio
• B. Techniques to measure red cell
  deformability
• 1. filtration
• 2. micropipette
• 3. Ektacytometry (Vidometry)
• IV. Other cytoplasmic components and red cell
  metabolism
• A. Glucose metobolism?
• glycolysis and the
  hexomonophosphate shunt
• B. Protective mechanisms against
  oxidative damage

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Lecture Outline

• III. Red cell deformability ( A brief review )
• A. Factors affecting red cell deformability
• 1. Cytoplasmic viscosity
• 2. intracellular rubbish
• 3. membrane rigidity
• 4. surface to volume ratio
• B. Techniques to measure red cell
  deformability
• 1. filtration
• 2. micropipette
• 3. Ektacytometry (Vidometry)
• IV. Other cytoplasmic components and red cell
  metabolism
• A. Glucose metobolism?
• glycolysis and the
  hexomonophosphate shunt
• B. Protective mechanisms against
  oxidative damage

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Glucose metabolism

• Luebering-Rapoport shunt

Fig 2.10

• Hexose monophosphate shunt pathway

• Embden-Meyerhof glycolytic pathway

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Oxidative stress and the protective mechanism
Oxy Hb
Met Hb
In red cells, there is a Met Hb reductase which
can use NADH to regenerate Hb
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Protective systems in cells against peroxidative
reactions
NADPH
H2O
ROH
GSSG
Hexose Monophosphate Shunt(G6PD)
Glutathione Peroxidase
Glutathione Reductase
Superoxide Dismutase
Catalase
O2
G-6-P
H2O2
ROOH
NADP
GSH
Met Hb Reductase to regenerate Hb using NADH
Glutathione Synthetase
Fe3
Amino Acid
OH
Vit. E ( oxid. Vit. E can be recycled by Vit. C )
Damage Cellular components leading to accelerated
cell removal