Delayed hemolysis of human erythrocytes in solutions of glucose

There has been described a type of hemolysis which occurs under certain defined conditions when erythrocytes are suspended in glucose solution. It consists of a prolytic phase lasting about an hour, followed by a hemolytic phase lasting about 2 hours. The physical factors controlling this delayed hemolysis have been investigated. The system is especially sensitive to changes of pH and of temperature. This type of hemolysis is inhibited by increased osmotic pressure and by phlorhizin, but not, as far as can be ascertained, by fluoride or iodoacetate. It is possible, but not yet proved, that delayed hemolysis in glucose solution is dependent on enzymic activity. Phosphorylation may be the limiting factor. During the prolytic phase the cells are easily permeable to potassium. It is concluded that the development of cation permeability is not a direct cause of hemolysis.     

The effect of pH, potassium, sodium, bicarbonate, and chloride ions and glucose on the buoyant density distribution of human erythrocytes in bovine serum albumin gradients

The effect of pH on the buoyant density of human erythrocytes at 4°C in bovine serum albumin (BSA) gradients has been reinvestigated. The results obtained disagree with those found by Legge and Shortman. This disagreement is due to a difference in the way “isotonic” is defined. The results in this pH study were obtained by keeping the total concentration of cations constant rather than the total concentration of solutes. This study demonstrated that when the pH of the BSA gradient is maintained between 5.7 and 7.2, by varying only the concentrations of bicarbonate and chloride ions, the value of _ρtmed, the buoyant density at the truncated median of the density distribution, for human erythrocytes changes in a complex manner, but does not increase anywhere as much as previously found. The bicarbonate ion apparently is partially excluded from the human erythrocyte. Upon extrapolation to the physiological concentration of the bicarbonate ion (27.50 meq/liter), the buoyant density was found to decrease with the increasing pH. Variations in the (K⁺/Na⁺) ratio of the BSA gradient media, at a constant pH and total cation concentration, do not appear to affect significantly the buoyant density of the human erythrocyte. Increasing the concentration of glucose from 5.55 to 11.10 meq/liter also did not significantly affect the buoyant density of these cells.     

Effects of sodium chloride,guanidine hydrochloride,and sucrose on the viscoelastic properties of sodium hyaluronate solutions

Effects of sodium chloride (NaCl), guanidine hydrochloride (GuHCl), or sucrose on the viscoelasticity of sodium hyaluronate (NaHA) solutions were studied. NaCl and GuHCl decreased both storage and loss moduli, while sucrose increased both moduli. The critical concentration C* was determined as an inflection point in the plot of zero shear specific viscosity vs concentration for NaHA solutions with and without NaCl, GuHCl, or sucrose. It is suggested that sodium ions or guanidinium ions shield the electrostatic repulsion of NaHA molecules, hence reduce the coil dimension, and C* shifted to higher concentrations. However, sucrose enhances the entanglement coupling between NaHA molecules and retards the disentanglement of molecular chains or promotes to create hydrogen bonds, and then C* for NaHA solutions with sucrose shifts to lower concentrations. This is in agreement with the results of light scattering measurements in the presence of 0.2M NaCl. Both the radius of gyration and hydrodynamic radius of NaHA were reduced in dilute solutions by the addition of sucrose, and added sucrose enhances the interaction between NaHA monomer units. In the case of concentrated NaHA solution, such interactions result to increase the storage and loss moduli because of the enhancement of temporary network formation. © 1999 John Wiley & Sons, Inc. Biopoly 50: 23–34, 1999     

Uptake and removal of cortisol by canine erythrocytes in various electrolyte solutions

The uptake of free cortisol by canine RBC was studied by incubating the cells in various Ringer-Locke solutions, saline, plasma, and plasma to which EDTA was added. The uptake of cortisol by RBC was similar in all electrolyte solutions; however, uptake was significantly less when RBC were incubated in plasma. The removal of both exogenous and endogenous cortisol from RBC was studied by washing the cells in various electrolyte solutions. Although the percentages of steroid removed per wash were not significantly different when cells were washed with Ringer-Locke solutions, saline washed RBC to which no cortisol was previously added gave significantly less steroid per wash. These data indicate that Na⁺, K⁺ and Ca⁺⁺ do not affect the permeability of these cells to cortisol and that the cortisol associated with canine RBC is loosely bound.     

Joint effects of sodium chloride,glutamine, and glucose in mouse preimplantation embryo culture media

A new medium, SOM, produced by simplex optimization, has been used to study the joint effects of NaCl, glutamine, and glucose on the development of outbred CF1 mouse zygotes to the blastocyst stage. Contrary to previous reports, glucose has no significant inhibiting effect on development to the blastocyst stage in this medium. Even in the presence of 5 mM glucose, 70% of the embryos develop to at least four cells, and 60% reach the blastocyst stage. Raising the concentration of NaCl from 75 to 125 mM, in the absence of glutamine, progressively inhibits development. Moreover, the response to glutamine depends on the concentration of NaCl in the medium. When the NaCl concentration is low, glutamine inhibits development. In contrast, when the NaCl concentration is high, glutamine protects against the inhibitory effect of the salt. We propose that glutamine protects against high concentrations of NaCl in the medium by acting as an organic osmolyte.     

Conformation of xanthan dissolved in aqueous urea and sodium chloride solutions

Quasielastic light-scattering and other physical-chemical techniques have been used to compare the conformation and intermolecular interactions of xanthan in water, aqueous sodium chloride, and urea solutions. The results showed that xanthan dissolved in 4m urea has a disordered conformation after the solution has been maintained for 3 h at 95° and then cooled to room temperature. This conformation is similar to that previously observed only in solutions having low ionic strength at higher temperatures, following disruption of the ordered, low-temperature form. “Anomalous” behavior is seen for xanthan as a function of ionic strength, in that the hydrodynamic radius increases with increase in ionic strength, whereas a decrease is typical for polyelectrolytes. These observations suggest that aggregation of rod-like chains, similar to that seen for other stiff-chain polymers, occurs for xanthan in salt solutions, where the charged groups of the polyelectrolyte are screened by the salt ions. This aggregation may explain some of the high values reported in the literature for the molecular weight.     

Enhancement of glutathione levels in mouse peritoneal macrophages by sodium arsenite, cadmium chloride and glucose/glucose oxidase

Glutathione content of mouse peritoneal macrophages markedly increased when they were exposed to insulting agents like sodium arsenite, cadmium chloride, and glucose/glucose oxidase which generates hydrogen peroxide. This increase was attributed to the induction of the cystine transport activity by these agents. The transport activity for other amino acids was not induced, but rather diminished by these agents. Heat shock treatment did not induce the cystine transport activity, nor did it augment glutathione. Since glutathione protects cells against the cytotoxic effects of these agents, the induction of the cystine transport activity constitutes a protective mechanism related to the stress caused by the agents. The protein component(s) for cystine transport may fall into the category of the stress protein.