A study of shape changes and the modulation of lytic susceptibility in erythrocytes

Thomas, Ade (1979) A study of shape changes and the modulation of lytic susceptibility in erythrocytes. PhD thesis, University of Glasgow.

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Conductimetric techniques were used to study the action of glutaraldehyde on the response of erythrocytes to lytic agents. Modulation of cell response to fatty acids could be increased 200-fold in fixed cells. Studies with ghosts suggest that sensitisation is predominantly a membrane phenomenon. Comparative studies of oleic acid distribution in normal and sensitised erythrocytes indicate that added fatty acid is evenly distributed in normal cells, but may be excluded from the vicinity of membrane proteins in fixed cells. The action of bee venom phospholipase A2 on fixed and unfixed erythrocytes is consistent with greater distortion of the lipid bilayer in sensitised cells. The most effective inhibitors of the sensitised leakage response were multivalent cations, chloropromazine and valinomycin. This suggests that modulation of the response to lytic agents in fixed cells involves membrane areas rich in polar phospholipids and of relatively low fluidity. Comparative studies of the physico-chemical effects of glutaraldehyde on membrane components showed extensive cross linkage of phosphatidyl serine and phosphatidyl ethanolamine and of the spectrin family of proteins but of few other membrane structures. Studies of the behaviour of fixed cells in hypotonic medium showed that resistance to osmotic lysis occurs in two stages and that the first stage correlates with the cross-linkage of the spectrin polypeptides. Induction of shape changes in erythrocytes by mild glutaralde-hyde treatment appears to require redistribution of membrane components and suggests that polymerisation of the spectrin polypeptides is the trigger for structural reorganisation of the membrane. It is suggested that the sensitised state is a transitory period in the shape change process resulting from a topological redistribution of membrane structures which is predominantly triggered by spectrin cross-linkage and that this membrane reorganisation under-lies the shape changes. The partial inhibition of cross-linkage of membrane proteins in erythrocyte ghosts by multivalent cations (Ca2+ and Fe3+, but not Mg2+ and La3+) suggests that the interaction of spectrin components with other membrane structures may depend substantially on the conformational states of the proteins.

Item Type: Thesis (PhD)
Qualification Level: Doctoral
Subjects: Q Science > QH Natural history > QH345 Biochemistry
Colleges/Schools: College of Medical Veterinary and Life Sciences
Supervisor's Name: Lawrence, Dr. A.J.
Date of Award: 1979
Depositing User: Enlighten Team
Unique ID: glathesis:1979-83105
Copyright: Copyright of this thesis is held by the author.
Date Deposited: 31 Aug 2022 08:04
Last Modified: 31 Aug 2022 08:04
Thesis DOI: 10.5525/gla.thesis.83105
URI: https://theses.gla.ac.uk/id/eprint/83105

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