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Introductory remarks: Transport mechanisms across cell membranes

Published online by Cambridge University Press:  23 August 2011

J. C. Ellory
Affiliation:
Department of Physiology, University of Oxford, Parks Road, Oxford OX1 2PT
B. C. Elford
Affiliation:
Department of Physiology, University of Oxford, Parks Road, Oxford OX1 2PT
C. I. Newbold
Affiliation:
Nuffield Department of Clinical Medicine, John Radcliffe Hospital, Headington, Oxford OX3 9DU

Extract

The differential permeability of cell membranes to various electrolytes and non-electrolytes represents one of the most fundamental characteristics of life. In the context of parasitology, differences in transport properties when parasite and host cells are compared represent an important avenue for chemotherapy. For example, a recent success in this area exploits the difference in nucleoside transport systems between host and parasite to produce combination therapy of Schistosoma japonicum by tubercidin and nitrobenzylthioinosine-5′-monophosphate (Elkouni, Diop & Cha, 1983). The morning session of this symposium was devoted to various aspects of membrane structure and function, particularly in the context of characterizing parasite transport systems. It is therefore probably worth while to present a simple classification of membrane transport systems, based on their complexity, and energy requirements. Table 1 summarizes the principal types of transport to be considered, starting with simple (Stokesian) diffusion. This will depend on permeant size, charge and lipid solubility. Classically, transmembrane transport of such molecules as aliphatic alcohols, ureas and small sugars has been studied, in simple systems such as the red cell (see Stein (1986) for references). In fact this route is important for intracellular delivery of a variety of hydrophobic molecules, for example phenylalanine benzyl ester transport as an antisickling agent (Acquaye, Young, Ellory, Grecki & Wilchek, 1983), or quin-2 and fura-2 for intracellular calcium measurements (Tsien, 1981).

Type
Research Article
Copyright
Copyright © Cambridge University Press 1988

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References

REFERENCES

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