1. Chang Gung University Department of Medical Biotechnology Clinical Hematology
Biology of the Red Cell IV & V﹕ Membrane and other cytoplasmic components
Dr. Chiu
Spring, 2012

2. 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. Ca+2 Homeostasis
C. Anion exchange

3. Lecture Outline V. Required reading VI. References
Text (Essential Haematology): pp
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 pp
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: , 1997.

4. 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. Ca+2 Homeostasis
C. Anion exchange

5. The red cell membrane structure

6. Biological Membranes as Bilayer Couples
Biological Membranes as Bilayer Couples. A Molecular Mechanism of Drug-Erythrocyte Interactions
Sheetz MP, Singer SJ. Proc Natl Acad Sci U S A Nov;71(11):

7. 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.

8. Membrane bilayer coupling
with changing RBC morphology

9. A schematic representation of the red cell membrane structure
Sphinomyeline (SM)
Phosphatidylcholine (PC)
Phosphatidylethanoline (PE)
Phosphatidylserine (PS)

10. C. Asymmetry of membrane
phospholipids

11. 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. Ca+2 Homeostasis
C. Anion exchange

12. Osmotic fragility

13. 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

14. 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

15. Glucose metabolism Luebering-Rapoport shunt
Fig 2.10
Embden-Meyerhof glycolytic pathway
Hexose monophosphate shunt pathway

16. 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

17. Protective systems in cells against peroxidative reactions
NADPH
H2O
ROH
GSSG
Hexose
Monophosphate
Shunt(G6PD)
Glutathione
Peroxidase
Glutathione
Reductase
Superoxide
Dismutase
Catalase O2
H2O2
ROOH
GSH
NADP
G-6-P
Met Hb
Reductase
to regenerate
Hb using NADH
Glutathione
Synthetase
Fe3+ OH
Amino Acid
Vit. E ( oxid. Vit. E can be recycled by Vit. C )
Damage Cellular components leading to accelerated cell removal