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PubMed1959

Effect of antibody and complement on permeability control in ascites tumor cells and erythrocytes.

Rabbit antibody + complement alters the permeability properties of mouse Krebs ascites tumor cells and erythrocytes. When antibody + C' acts on ascites tumor cells in a low protein medium, intracellular K(+) is lost from the cells at a rate far greater than the normal leak rate. At the same time the cells lose amino acids and ribonucleotides and become fully permeable to the Na(+) of the medium. When antibody + C' acts in a low protein medium, the cells swell extensively and lose most of their macromolecules to the medium (hemoglobin from erythrocytes, protein and RNA from the ascites tumor cells). If the antibody + C' acts in a medium containing protein in sufficient concentration to balance the colloid osmotic pressure of the cells, the swelling is prevented; no macromolecules are then lost from the cells, but the loss of K(+) and entrance of Na(+) are not altered, and the loss of amino acids and ribonucleotides is only slightly affected. It therefore appears that the action of antibody + C' is to produce functional "holes" in the animal cell membrane which permit the equilibration of cations and small molecules between cell and medium. This leads to an increase in the osmotic pressure of the cell and a rapid influx of water. The cell membrane and its "holes" are thereby stretched, permitting macromolecules to escape from the cell.

Animals↗
PubMed1960

The electrophoretic velocity of human red cells, of their ghosts and mechanically produced fragments, and of certain lipid complexes.

Ghosts prepared in CO(2)-saturated water from unwashed human red cells can be fragmented mechanically, but ghosts from thrice washed cells cannot. If the ghosts are prepared by freezing and thawing, this difference is not observed. The electrophoretic velocity varies also with the way in which the ghosts are prepared. The pH-mobility dependence of washed red cells flatten off to a plateau at pH 9, and the electrophoretic velocity is zero at about pH 2. Ghosts prepared by freezing and thawing have almost the same pH-mobility dependence, but if the ghosts are prepared in CO(2)-saturated hyptonic saline, the mobility at pH 9.4 is 0.75 times that of washed cells. Fragments of ghosts of unwashed red cells have a smaller mobility than that of the red cells. Trypsin reduces the mobility of washed red cells and of ghosts. Sols of lipid complexes (lecithin, cephalin, and lipositol), at varying pH's, have a mobility 1.2 times that of the washed red cell. The pH-mobility relation is otherwise similar. These complexes can be coated with dextran and trypsin.

Erythrocyte Membrane↗
PubMed1960

The influence of pH and ionic strength on the electrokinetic stability of the human erythrocyte membrane.

The electrokinetic stability of washed normal human erythrocytes is discussed from the point of view of pH, ionic strength, and composition of the suspending medium. Many of the electrophoretic characteristics at low ionic strengths (sorbitol to maintain the tonicity), such as the isopotential points, are shown to arise principally from adsorption of hemolysate. The concept of electrokinetically stable, metastable, and unstable states for the red cell at various ionic strengths is introduced in preference to the general term "cell injury." In the stable state which exists around pH 7.4 for ionic strengths >0.007, no adsorption of hemolysate occurs, in the metastable state reversible adsorption of hemolysate occurs, and in the unstable state, in which ionic strengths and pH ranges are outside the metastable range, the membrane undergoes irreversible hemolysate adsorption or more general hydrolytic degradation. It is deduced from the equivalent binding of CNS, I, Cl, and F, the pH mobility relationships, and the conformation of the ionic strength data in the stable state to a Langmuir adsorption isotherm, that the membrane of the human erythrocyte behaves as a macropolyanion whose properties are modified by gegen ion association and in some instances by hemolysate adsorption. The experimental results are insufficient to establish conclusively the nature of the ionogenic groupings present in the membrane interphase.

Erythrocyte Membrane↗
PubMed1960

Regulation of cell volume by active cation transport in high and low potassium sheep red cells.

A model cell which controls its cation composition and volume by the action of a K-Na exchange pump and leaks for both ions working in parallel is presented. Equations are formulated which describe the behavior of this model in terms of three membrane parameters. From these equations and the steady state concentrations of Na, K, and Cl, values for these parameters in high potassium (HK) and low potassium (LK) sheep red cells are calculated. Kinetic experiments designed to measure the membrane parameters directly in the two types of sheep red cells are also reported. The values of the parameters obtained in these experiments agreed well with those calculated from the steady state concentrations of ions and the theoretical equations. It is concluded that both HK and LK sheep red cells control their cation composition and volume in a manner consistent with the model cell. Both have a cation pump which exchanges one sodium ion from inside the cell with one potassium ion from outside the cell but the pump is working approximately four times faster in the HK cell. The characteristics of the cation leak in the two cell types are also very different since the HK cells are relatively more leaky to sodium as compared with potassium than is the case in the LK cells. Both cell types show appreciable sodium exchange diffusion but this process is more rapid in the LK than in the HK cells.

Animals↗
PubMed1960

Tracer exchange vs. net uptake of glucose through human red cell surface. New evidence for carrier-mediated diffusion.

Previous kinetic studies of net sugar movements through the human erythrocyte surface (in response to concentration gradients) have led to postulation of a special "carrier" system for transfer of monosaccharides in these cells. But alternatively some sort of non-specific depression of cell permeability at high sugar concentrations has been suggested as a possible basis for the saturation kinetics and the competitive phenomena observed. New theoretical calculations show that these two interpretations predict entirely different orders of magnitude for the relative rate of tracer glucose exchange at such high sugar levels. Therefore, the speeds of gross chemical equilibration and of tracer glucose equilibration were compared by means of serial analyses on quickly separated cells and media, in thick red cell suspensions. Glucose was first added to glucose-free suspensions, and its entry into the cells followed; then C14-glucose was added after attainment of chemical equilibrium, and the tracer equilibration similarly followed. The speed of the tracer movement in relation to the speed of net uptake was on the order of 50 to 100 times greater than would be found in an uncomplicated diffusion process, regardless of what depressant effect might be occasioned by the high sugar levels. In contrast, the comparative rates observed are predicted by the previously proposed facilitated-diffusion mobile-carrier model for monosaccharide transfer, if the glucose-carrier complex is assigned a dissociation constant (at 20 degrees C.) in the neighborhood of 1 mM.

Biological Transport↗
PubMed1960

Efflux and influx of erythrocyte water.

Rabbit erythrocytes were washed in buffered NaCl solutions isotonic with rabbit serum (Delta(t) -0.558 degrees C.) and suspended in buffered NaCl solutions of tonicity equidistant from intracellular tonicity (Delta(t) = -0.558 degrees C. +/- 0.112 degrees C.) of varying pH and incubated at varying temperatures. After incubation, the freezing point depression (Delta(t)) was measured on the supernatant. Change in the Delta(t) measured change in the water content of the extracellular solutions-water being withdrawn by erythrocytes (W(I)) from the hypotonic solutions and added (W(E)) to the hypertonic solutions. W(E) was always less than W(I) and was inversely proportional to the pH in the range 6.5-8.0. W(E) was significantly increased by lowering the temperature of the cell suspension to 4 degrees C. W(I) was increased by raising or lowering the pH or raising the temperature of the cell suspension. W(E) x W(I) not equal k. W(E) and W(I) were affected differently by changes in pH and temperature. It was concluded that W(E) and W(E) were probably under different physicochemical control.

Erythrocytes↗
PubMed1962

The active transport of sodium by ghosts of human red blood cells.

The outflux of Na(24) from prelabeled ghosts was measured under various conditions. Prelabeling was accomplished by hypotonic hemolysis of intact human cells in the presence of tracer Na(24). The resultant ghosts when subsequently washed were found to retain 10 to 20 per cent of the initial Na(24). Separate experiments indicated that this trapped amount resides in only a portion of ghosts comprising the total population. The characteristics of the outflux of this residual Na(24) indicated that the ghost system closely resembles intact red cells. The outflux of Na from ghosts could be divided into three components: active and passive transport and exchange diffusion. The active transport system, necessarily driven by metabolism, required the presence of K in the extracellular phase and was blocked by strophanthidin. The concentration dependence of the Na pump flux on the external K and internal Na appeared the same in ghosts as in intact cells. Certain other features of this ghost system are also discussed.

Biological Transport↗