26
A . M O S C O N A , O . A . T R O W E L L A N D E . N . W l L L M E R
been recognized as essential requirements for physiological salt solutions,
but since the early days of Tissue Culture there have been few systematic
studies on the optimal concentrations of these salts for the various tissues.
As mentioned above, in connexion with osmotic pressure, the actual
concentrations of ions in their own right are often important and it may
well be that the relative concentrations of these salts are also of more
importance in determining the behaviour of different types of cells
than has previously been supposed. In recent work on the protozoan
Naegleria the form which this organism adopts, amoeboid or flagellate,
is very sensitive to the ionic concentrations in its surroundings, positive
ions tending to favour the amoeboid form, negative ions the flagellate,
though each ion has to be considered separately, since they all have
their own special effects. For example, ImM N a H C 0 3 favours the
flagellate form but in the same concentration of N a 2 S 0 4 most of the
Naegleria remain as amoebae (Willmer, 1956). Moreover, the proportions of calcium and magnesium can determine which form the organism adopts. It is not unlikely, therefore, that similar changes of cell
activity may occur with other cells also, even in multicellular organisms.
Parathyroid cells, for example respond to changes in the C a
++ content of
the blood.
Similarly, it is now known that the chloride ion can no longer be
taken for granted, as it has frequently been in the past, since certain
types of cell at least, e.g. oxyntic cells of the stomach, and chloride
secretory cells in the gills of fish, have powers of moving it across their
membranes and some can treat it quite differently from the bicarbonate, nitrate, sulphate and other small anions. Nor does it necessarily
follow the movement of N a
+ . Sulphate ions have also been shown to be
of importance to some types of cell, particularly to those concerned
with the production of sulphated polysaccharides either internally,
as in goblet cells, or externally as in cartilage cells (Pelc and Gliicksmann,
1951; Jennings and Florey, 1956; Johnston and Comer, 1957). On
the other hand, a keratinizing epithelium, which requires sulphur for
the production of keratin, must be supplied with cysteine, cystine or
methionine.
The actions of certain steroid hormones, e.g. aldosterone, progesterone and oestradiol are known to affect the ratio of K
+ to N a
+
in body fluids and in certain classes of cells, and to bring about changes
in the activities of these cells. In tissue cultures there have been relatively few studies which take this sort of situation into account and to
give cells in vitro their normal ionic surroundings and their normal
complement of circulating hormones is at present quite beyond the
range of what is feasible. This lack of knowledge of the effects of ions
on cells in vitro does not, however, detract from the probable importance
A . M O S C O N A , O . A . T R O W E L L A N D E . N . W l L L M E R
been recognized as essential requirements for physiological salt solutions,
but since the early days of Tissue Culture there have been few systematic
studies on the optimal concentrations of these salts for the various tissues.
As mentioned above, in connexion with osmotic pressure, the actual
concentrations of ions in their own right are often important and it may
well be that the relative concentrations of these salts are also of more
importance in determining the behaviour of different types of cells
than has previously been supposed. In recent work on the protozoan
Naegleria the form which this organism adopts, amoeboid or flagellate,
is very sensitive to the ionic concentrations in its surroundings, positive
ions tending to favour the amoeboid form, negative ions the flagellate,
though each ion has to be considered separately, since they all have
their own special effects. For example, ImM N a H C 0 3 favours the
flagellate form but in the same concentration of N a 2 S 0 4 most of the
Naegleria remain as amoebae (Willmer, 1956). Moreover, the proportions of calcium and magnesium can determine which form the organism adopts. It is not unlikely, therefore, that similar changes of cell
activity may occur with other cells also, even in multicellular organisms.
Parathyroid cells, for example respond to changes in the C a
++ content of
the blood.
Similarly, it is now known that the chloride ion can no longer be
taken for granted, as it has frequently been in the past, since certain
types of cell at least, e.g. oxyntic cells of the stomach, and chloride
secretory cells in the gills of fish, have powers of moving it across their
membranes and some can treat it quite differently from the bicarbonate, nitrate, sulphate and other small anions. Nor does it necessarily
follow the movement of N a
+ . Sulphate ions have also been shown to be
of importance to some types of cell, particularly to those concerned
with the production of sulphated polysaccharides either internally,
as in goblet cells, or externally as in cartilage cells (Pelc and Gliicksmann,
1951; Jennings and Florey, 1956; Johnston and Comer, 1957). On
the other hand, a keratinizing epithelium, which requires sulphur for
the production of keratin, must be supplied with cysteine, cystine or
methionine.
The actions of certain steroid hormones, e.g. aldosterone, progesterone and oestradiol are known to affect the ratio of K
+ to N a
+
in body fluids and in certain classes of cells, and to bring about changes
in the activities of these cells. In tissue cultures there have been relatively few studies which take this sort of situation into account and to
give cells in vitro their normal ionic surroundings and their normal
complement of circulating hormones is at present quite beyond the
range of what is feasible. This lack of knowledge of the effects of ions
on cells in vitro does not, however, detract from the probable importance