Cellular Aspects of Membrane Permeability

284 Pages·1967·9.131 MB·English

by  E. Schoffeniels, P. Alexander and Z. M. Bacq (Auth.)

CELLULAR ASPECTS OF
MEMBRANE PERMEABILITY
BY
E. SCHOFFENIELS
PERGAMON PRESS
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Copyright © 1967
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First edition 1967
Library of Congress Catalog Card No. 66-29668
2976/67
A MON MAITRE M. FLORKIN
PIONNIER DU COMPARATISME
EN BIOCHIMIE
Hypotheses like living organisms must grow
and evolve. _ ^_^
0 τ τ τ
BARRINGTON
... les phenomenes physiques et chimiques
de Vorganisme ont dans Vetre vivant des
conditions qu'ils rfont par ailleurs.
CLAUDE BERNARD
INTRODUCTION
MEMBRANE permeability has long been of interest to biologists as well as to
workers involved in other branches of experimental science because ex-
changes between two phases or across the boundaries of the phases are
commonly encountered in many fields of science.
In biology exchange across boundaries is of the utmost importance and it
is difficult to study a biological function without encountering a problem of
permeability, whatever the theoretical or methodological approach the
investigator may have with regard to such concepts as "membrane",
"barriers", cell structure and the like. The secret of life lies in ordered mole-
cular structures constituting integrated metabolic networks. Consequently,
all matter entering or leaving a living cell or organism is involved in coupled
catalysed processes with no prolonged contact of a reaction product with
the macromolecule which catalysed the reaction. Thus most of the biological
problems are concerned with permeation of matter through well-organized
ultrastructure. Since about 1950, important progress has been made and a
great deal of new information has been accumulated on the problem of
membrane permeability. These spectacular advances did not of course solve
the fundamental aspects of the problem but they have prepared a favourable
ground on which new hypotheses may be built.
It is the purpose of this monograph to give not only an account of the
actual state of the knowledge with regard to permeability problems but
also to reinterpret the experimental findings within the framework of new
working hypotheses. It is also proposed to look at some of these problems
of membrane permeability from a biochemical point of view in explaining
the origin and adaptations of animal life.
Classically, the origin of life is explained either by the "vital force"
theory or, if it is rejected as it must be by a scientist, by the known laws of
physics and chemistry. The very common, mechanistic view is that all that
happens in the organism is logically derivable from physics and chemistry.
This view is, however, false as already pointed out by Claude Bernard in his
"Legons sur les Phenomenes de la Vie". Life represents an organization of
matter which is qualitatively quite different from that of matter in other
forms and we already know from physics that different laws are re-
quired to explain phenomena involving for example the very small or the
very large. What we know so far about the structure of living matter indi-
cates that we must be prepared to find it working in a manner that cannot
be reduced to the ordinary laws of physics not because of any new forces
la MP IX
X INTRODUCTION
but because of the difference in construction. The assumption of contem-
porary biology that the combination of the known laws of physics and
chemistry with Darwin's theory and the idea of chance mutations can
satisfactorily explain life and evolution seems rather doubtful.
The systematist's interpretation of evolution and phylogenic relationships
rests upon the morphological or embryological studies of a wide range of
species. My basic view is that the comparative study of membrane perme-
ability offers new material for discussion and a new approach to the problem
of evolution and speciation. Biologists have always felt very uneasy as far
as these problems are concerned. Transformism, darwinism, mutationism,
neo-darwinism, none of these theories are entirely satisfactory for the simple
reason that none takes into account the intimate molecular mechanism
responsible for a biological function or the specific arrangement at the level
of molecular organization responsible for morphological or embryological
characteristics. To lay the basis of a new theory of evolution (and thus
speciation) one should consider at the molecular scale one important func-
tion of living matter and look how the problem has been solved throughout
the animal kingdom.
Biology is now in a state of transition. We realize at last that our methodo-
logical approaches are outdated and cannot be of much help as far as biolo-
gical functions are concerned/For going beyond a purely descriptive state,
we must turn to new theoretical approaches and interpret our observations
in terms of mechanisms. In fact we are now in the same situation experienced
by the physicists when they discovered the sub-atomic world; they could
not describe the properties of a wave in terms of corpuscles. But in contradic-
tion to what they experienced, biology has not yet found its new theoretical
foundations. This particular aspect of the problem is specially acute in the
field of permeability as will be exemplified in this book.
It may be appropriate to give some explanation with regard to the presen-
tation of the subject matter in the following pages. The matter is divided
into three main parts. This division reflects the way of thinking many workers
in the field have experienced. This may be summed up in the following
way. A biologist wants to know something about the function of an epithe-
lium separating fluids of different composition. The first problem to be
solved is to know what is going through and what is not, as well as the driv-
ing forces responsible for the observed displacements. In other words the
permeability characteristics of the experimental object have to be defined.
This aspect of the work is thus closely related to the activity of a taxo-
nomist defining the various morphological features he encounters in the study
of animal species. When the epithelium is permeable to various substances,
electrically charged or not, we should ask ourselves whether all those sub-
stances cross the epithelium through the same locus or not, i.e. what is the
spatial distribution of the permeability characteristics. An important aspect
of the cellular differentiation lies in the spatial distribution of the perme-
INTRODUCTION XI
ability characteristics at the surface of the cell. Thus as a systematician,
knowing a set of morphological features, identifies plants or animals, we
may identify a living membrane by knowing its permeability characteristics
as well as their spatial distribution.
Finally two more questions should be asked: what is the chemical nature
of the molecular architecture responsible for permeability characteristics
and what is its physical nature?
This book is mainly concerned with functional studies of membranes.
However, a few references to the problem of evolution, speciation and so
on will be given in the text in order to substantiate our proposition that a
biochemical approach to the problems of membrane permeability may help
to understand the animal organization and the history of its fascinating
adaptations.
la*
ACKNOWLEDGEMENTS
I would like to thank the many editors and publishers of the journals and
books who have allowed me to reproduce the following figures.
Figures 1.3, 1.4, 1.5, reproduced from The American Journal of Physiology.
Figures 2.1, 4.2, 4.3, 8.1, 8.2, 8.3, 8.4, reproduced from Ada Physiologica
Scandinavica.
Figures 2.3, 2.5, 2.6, 2.7, 2.8, 3.1, 5.1, 5.2, 9.8, 9.9, 9.10, 9.11, 9.13, 12.4,
13.1, 13.3, reproduced from Biochimica et Biophysica Acta.
Figures 5.3, 11.5, reproduced from The London Journal of Physiology.
Figure 8.5, reproduced from the Journal of Clinical Investigation.
Figures 8.6, 9.2, 9.3, reproduced by permission of the Rockefeller University
Press from The Journal of General Physiology, 1965, vol. 48, page
427, figure 1: ibid. 1939, vol. 22, page 655, figure 4: ibid. 1939,
vol. 43, page 1185, figure 7.
Figures 9.6, 9.14, reproduced from the Proceedings of the Royal Society
(London), Series B.
Figure 9.7, reproduced from NACHMANSOHN, Chemical and Molecular Basis
of Nerve Activity, Academic Press, N.Y.
Figures 11.3, 11.4, 11.6, reproduced from Nature.
Figure 11.7, reproduced from the Canadian Journal of Biochemistry and
Physiology.
Figures 14.1, 14.5, 14.7, reproduced from J. B. FINEAN, Chemical Ultra-
structure in Living Tissues, 1961. Courtesy of Charles C. Thomas,
Publisher, Illinois.
I am also greatly indebted to the many friends and colleagues who have
lent me the original pictures reproduced in this book. Special thanks are due
to: A. D. Bangham, R. Bronchart, M. G. Farquhar, H. Fernandez-Moran,
G. E. Palade, J. D. Robertson, F. S. Sjöstrand, Tiberio, C. L. Voute, and
T. E. Weier.
My final though no less heartfelt thanks are due to Mrs. Gh. Duchäteau-
Bosson for her devoted assistance in correcting the proofs.
Xlll
PART I
THE PERMEABILITY CHARACTERISTICS
OF LIVING MEMBRANES
IT IS well known that the composition of a living cell is very different from
that of its surrounding medium. In a pluricellular aquatic animal it is also
known that the internal medium of a living cell can differ from its external
medium. These differences have been variously interpreted, giving rise to
many hypotheses and theories. On purely theoretical grounds, it is evident
that, by its very nature, life in all its manifestations is a reflection of a con-
tinuous exchange of matter between an organism and its surroundings. Thus
at least some parts of an organism must be "permeable" to the constituents
of the outside medium. This enables us to discard any hypothesis which
explains the difference in composition between an organism and its surround-
ings by assuming complete "impermeability" of the barrier limiting the
organism. Isotopic studies have substantiated this conclusion by showing
the generality of the principle of dynamic equilibrium at every level of cellular
organization including atoms in molecular structures.
The one point on which everyone agrees is that the unequal distribution
of ions and molecules between a cell and its surroundings is the result of
complex phenomena of influx and efflux of matter taking place at various
sites in the organism at the level of structures having well-defined properties,
generally with an expenditure of energy. However, where mechanisms of such
phenomena are concerned, there are conflicting views in the literature of the
last decade and these can be grouped in two main categories. The majority of
the workers in this field consider that a special structure surrounding the cell,
called the " cellular membrane ", is the site of the various mechanisms enabling
the cell to keep its contents in the particular state observed. The opponents of
this view assume that if such a thing as a membrane exists, it has no particu-
lar function; the unequal distribution of ions and molecules depends on the
very special properties exhibited by macromolecules in the intracellular
phase. It should, however be made clear at the very beginning that the
present author does consider that functionally the cellular membrane exists
and is the site of special mechanisms responsible for the unequal distribution
of ions and molecules.
As we shall show in the following pages, physical measurements carried
out on isolated cells are best interpreted if one postulates the existence of a
1
2 CELLULAR ASPECTS OF MEMBRANE PERMEABILITY
barrier, having special properties and surrounding the cell. Electrical mea-
surements of resistance, impedance, capacitance, potential difference, as
well as surface tension and diffusion studies, show that the cell interior is
separated from the extracellular fluid by a barrier exibiting a higher resis-
tance to the movement of water, ions and molecules, than the intra- and
extracellular fluid. Electrical properties of nerve indicate also that we are
dealing with a structure formed by a low resistance central core surrounded
by a component behaving like a poorly isolated capacity. Arguments
stemming from recent progress in light as well as electron microscopy studies
are also in favour of the existence of a morphological entity clearly differen-
tiated at the cell surface. The problem, and it is an important one, is, however,
to know if the functional barrier is related to what we see on the electron
micrograph. The discussion of this point is left to the last part of the book.
The concept of living membrane is sometimes misleading. When dealing
with an epithelium, the whole structure is called a living membrane; on the
other hand, the membrane of nerve or muscle fibres are cell membranes.
Obviously the permeability properties of an epithelium are directly related
to the properties of the epithelial cell membranes. It should therefore be
made clear that whatever the type of tissue considered in the last analysis
it is the properties of a cellular membrane that we are studying.
When dealing with pluricellular material, the possibility that certain
permeability characteristics may depend on some property of the intra-
cellular cement has also to be considered. At the outset we may however
mention that when demonstrable the intercellular cement plays a minor
role in the dynamic aspects of epithelial tissue permeability.