3. CELLULAR ASPECTS OF ACTIVE TRANSPORT
183
bility characteristics of the membrane. The hepatic uptake of a-aminoisobutyric acid and glycine is enhanced by the glucocorticoids (165). In
yeast cell and red blood corpuscle, the corticoids seem to inhibit the
extrusion of Na. This effect may be related to the decrease in intracellular Κ concentration observed in muscle fibers. In human red cell,
the uptake of phosphate is inhibited by deoxycorticosterone, whereas
cortisone decreases the uptake of fructose and glucose (166). In Neurospora crassa deoxycorticosterone inhibits the uptake of amino acids,
sugars, and Rb (167, 168).
Insulin, growth hormone, estradiol, and stilbestrol have also been
studied in relation to their effects on the permeability characteristics of
living membrane (168a^l71).
The uptake of α-aminoisobutyric acid
as well as glycine is increased in striated and smooth muscle by insulin,
estradiol, and growth hormone. The uptake of amino acids is also
enhanced in the Ehrlich ascites carcinoma cells in the presence of
estradiol. On the contrary, stilbestrol suppresses, at low concentration,
the glycine transport. This is, however, attributed to the effect of this
hormone as a respiratory inhibitor (172).
In muscle the uptake of Κ is increased by insulin
(173,174).
The results presented in this section emphasize the multiplicity of
transports that are affected by the same hormone. Passive permeability
(including well-demonstrated mediated transport) as well as active
transport of various substances are involved. This is to be related to
previous observations concerning the effect of quaternary ammonium
derivatives and other pharmacodynamically active agents on the permeability characteristics of living membranes. Since chemically related
substances can affect various permeability characteristics not only in cells
functionally different, but also in tissues belonging to zoological species
far apart in the systematic classification, it could be proposed that the
molecular architecture responsible for the various permeability characteristics of living membranes are chemically related, and that a common
biochemical system could be responsible for all the permeability characteristics of living membranes. This would thus mean that we could
consider the permeability characteristics as being a heterotypic expression of a common biochemical system (49, 175), this concept being used
here in the sense defined by Mason (176).
VII. Alkaline Earths and Permeability Characteristics of
Living Membranes
It is generally assumed that alkali metal ions have a well-defined role
in the production of bioelectric potentials, while a possible interaction
with cellular structure is seldom considered. On the contrary, this latter
183
bility characteristics of the membrane. The hepatic uptake of a-aminoisobutyric acid and glycine is enhanced by the glucocorticoids (165). In
yeast cell and red blood corpuscle, the corticoids seem to inhibit the
extrusion of Na. This effect may be related to the decrease in intracellular Κ concentration observed in muscle fibers. In human red cell,
the uptake of phosphate is inhibited by deoxycorticosterone, whereas
cortisone decreases the uptake of fructose and glucose (166). In Neurospora crassa deoxycorticosterone inhibits the uptake of amino acids,
sugars, and Rb (167, 168).
Insulin, growth hormone, estradiol, and stilbestrol have also been
studied in relation to their effects on the permeability characteristics of
living membrane (168a^l71).
The uptake of α-aminoisobutyric acid
as well as glycine is increased in striated and smooth muscle by insulin,
estradiol, and growth hormone. The uptake of amino acids is also
enhanced in the Ehrlich ascites carcinoma cells in the presence of
estradiol. On the contrary, stilbestrol suppresses, at low concentration,
the glycine transport. This is, however, attributed to the effect of this
hormone as a respiratory inhibitor (172).
In muscle the uptake of Κ is increased by insulin
(173,174).
The results presented in this section emphasize the multiplicity of
transports that are affected by the same hormone. Passive permeability
(including well-demonstrated mediated transport) as well as active
transport of various substances are involved. This is to be related to
previous observations concerning the effect of quaternary ammonium
derivatives and other pharmacodynamically active agents on the permeability characteristics of living membranes. Since chemically related
substances can affect various permeability characteristics not only in cells
functionally different, but also in tissues belonging to zoological species
far apart in the systematic classification, it could be proposed that the
molecular architecture responsible for the various permeability characteristics of living membranes are chemically related, and that a common
biochemical system could be responsible for all the permeability characteristics of living membranes. This would thus mean that we could
consider the permeability characteristics as being a heterotypic expression of a common biochemical system (49, 175), this concept being used
here in the sense defined by Mason (176).
VII. Alkaline Earths and Permeability Characteristics of
Living Membranes
It is generally assumed that alkali metal ions have a well-defined role
in the production of bioelectric potentials, while a possible interaction
with cellular structure is seldom considered. On the contrary, this latter