Effects of Tris and histidine on human erythrocytes and conditions influencing their mode of action

A hypothesis of the disc-sphere transformation of the erythrocytes between glass surfaces and of related observations

Erythrocytes suspended at a low hematocrit in a non-buffered isotonic saline change from biconcave discs to spheres between glass surfaces of a slide and of a coverslip with the echinocyte as an intermediate. A pH increase is a major factor responsible for this disc-sphere transformation or glass effect. It is also observed between surfaces made of various polymers and of mica provided that the distance between them is controlled (0.1 mm). The glass effect is antagonized by serum, plasma, serum albumin, ammonium salts and CO2. It is not observed above a 1-2% hematocrit, but is enhanced by gamma-globulins. The sites of reappearance of the spicules are the same and the order of their disappearance is the inverse of the order of their reappearance during the repetitive cycle of the disc-sphere transformation and reversal when a small glass rod is alternatively approached near a site on the erythrocyte surface and withdrawn. A mechanism of erythrocyte shape control has been previously hypothesized in which Band 3 (AE1), the anion exchange protein, plays a central role. Specifically, decrease and increase of the ratio of its outward-facing conformation (Band 3o) and inward-facing conformation (Band 3i) contract and relax the membrane skeleton, promoting the echinocytosis and stomatocytosis, respectively. The Band 3o/Band 3i equilibrium ratio is determined by the Donnan equilibrium ratio of Cl-, HCO3- and H+ (r=Cl(i)-/Cl(o)-=HCO3i-/HCO3o-=Ho+/Hi+), increasing with it. The mechanism could explain by a change of the Donnan ratio the above observations with the assumptions that polymers are permeable to CO2 and that an unstirred layer slows the propagation of the change occurring at the site of approach of the glass rod to peripheral sites. The presence of HCO3- in serum or plasma may be the basis for the absence of the glass effect in these fluids.

Transfer of Tris buffer and effects on K+ loss in human red blood cells and reconstituted ghosts

The rate of volume changes of human red blood cells in the presence of Tris-HCl is pH-dependent. At 37 degrees C, t 1/2 is 25-30 min at pH 7.4 and 10-20 min at pH 8.4. Hemolysis in Tris-HCl is delayed by H2DIDS but is promoted by low concentrations of bicarbonate. This bicarbonate effect has been reversed by inhibiting carbonic anhydrase with acetazolamide. K+ loss of red blood cells is increased at 37 degrees C in isotonic NaCl solutions containing in addition Tris-HCl. This Tris effect is enhanced from pH 6.4 to 8.4. At pH 8.4 K+ loss is stimulated about 3-fold by addition of 160 mM Tris-HCl. The onset of the Tris effect is delayed at pH 7.4 and below, but not at pH 8.4. Such a delay is absent after preincubation of the cells with Tris-HCl. After binding H2DIDS to red cells, no Tris-dependent increase of K+ loss has been observed. K+ loss of reconstituted red cell ghosts with equal internal and external chloride concentrations remained unaffected by Tris-HCl added to the external solution. In ghosts containing sucrose for isotonicity instead of choline chloride K+ loss is smaller but is stimulated by Tris-HCl approaching the rate in those ghosts with equal internal and external chloride concentrations. The transfer of Tris-HCl into red blood cells depends on the pH and on the chloride shift. As there is evidence that Tris-HCl raises the intracellular pH and reduces the Donnan potential at the membrane, K+ loss of red cells may be increased following an intracellular buffer interaction of hemoglobin and Tris-HCl.

Reaction of colloidal silica with membranes of intact mammalian cells

Colloidal silical particles were produced at a size that permitted reaction with human erythrocytes and rat macrophages without affecting cell integrity. Binding of colloid was shown by increased electrophoretic mobility of red cells and also resulted in changes in the surface topography of red cells as seen with scanning electron microscopy. The degree to which colloid binds to red cells was determined by microprobe analysis of single intact cells. Furthermore, the capacity of red cells to bind silica was increased if sialic acid residues were removed enzymatically from the cell surface.

Reduction of the sialic acid and galactose concentrations in erythrocyte membranes in alcoholics

The sialic acid and galactose concentrations in erythrocyte membranes were examined in 32 and 17 alcoholics respectively, during current abuse, and the sialic acid concentration in 10 patients after one and four weeks of abstention. During current alcohol abuse the concentrations of these two surface carbohydrates were decreased by an average of 10% and 16% respectively, when compared to matched, healthy controls (p less than 0.0005). After one and four weeks of abstention the sialic acid values were not significantly different from those of the controls suggesting that the abnormal cells were eliminated within one week after cessation of alcohol intake. No correlations were found between the sialic acid or galactose concentrations and peripheral red cell characteristics or serum liver enzyme levels. Hemolysis in isotonic Tris was significantly increased during current abuse, and was highly dependent on the sialic acid concentration at one particular stage of Tris-induced lysis. The mechanism behind the change of the oligosaccharide concentration of the membrane may either be increased hydrolytic cleavage or inhibition of the synthesis of glycoproteins and glycolipids. Previous similar findings in serum transferrin in alcoholics and in synaptosomes from young rat brain after ethanol exposure indicate that glycoprotein and glycolipid metabolism may be an important target, directly or indirectly, in the biological actions of ethanol.

Enhancement of (Ca2+ + Mg2+)-ATPase activity of human erythrocyte membranes by hemolysis in isosmotic imidazole buffer. I. General properties of variously prepared membranes and the mechanism of the isosmotic imidazole effect

1. Membranes prepared from human erythrocytes hemolyzed in isosmotic (310 imosM) imidazole buffer, pH 7.4, show enhanced and stabilized (Ca2+ + Mg2+)-ATPase activity compared with membranes prepared from erythrocytes hemolyzed in hypotonic (20 imosM) phosphate or imidazole buffer, pH 7.4. 2. Exposure of intact erythrocytes or well-washed erythrocyte membranes to isosmotic imidazole does not cause enhanced (Ca2+ + Mg2+)-ATPase activity. 3. Exposure of erythrocyte membranes, in the presence of isosmotic imidazole, to the supernatant of erythrocyte hemolysis or to a partially purified endogenous (Ca2+ + Mg2+)-ATPase activator, promotes enhanced (Ca2+ + Mg2+)-ATPase activity. Under appropriate conditions, NaCl can be shown to substitute for imidazole. The results demonstrate that imidazole does not act directly on the erythrocyte membrane but rather by promoting interaction between an endogenous (Ca2+ + Mg2+)-ATPase activator and the erythrocyte membrane.

Effects of growth conditions on the ion composition of Bifidobacterium bifidum subsp. pennsylvanicum

The cation content of Bifidobacterium bifidum subsp. pennsylvanicum was markedly influenced by the washing procedure of the cells, by the growth phase and the temperature, and by the composition of the culture medium. Optimal retention of cations was achieved by washing with 0.25 M MgCl2 at 20C. The intracellular Na+ concentration rose during growth in normal medium to a constant value in the stationary phase, the K+ concentration rose in the exponential phase, but fell in the stationary phase. Cells from 29-C cultures contained more Na+ and less K+ in the stationary phase than did cells from 37-C cultures, but the total cation content was the same at 29 and 37C. Intracellular Na+ and K+ concentrations were dependent on the concentrations in the medium and on its osmolarity. The intracellular Na+/K+ ratio varied from 0.04 to 2.3. The concentrations of Na+,K+ and phosphate in the medium hardly affected growth. Mg2+-deficiency of the medium markedly decreased the concentration of Mg2+ within the cell; its concentration in the cell sap was greatly affected, but the amount of sedimentable, bound Mg2+ only slightly. The content of K+ within the cell decreased in Mg2+-deficient medium, but the concentration of Na+ did not. Omission of Tween 80 as well as its substitution by Tween 20 caused a decrease of intracellular K+. Cells from Tween 40 and Tween 60 cultures additionally contained markedly less Na+.

Transitory postnatal hemolysis of calf red cells by amino acids

Among the amino acids which can be solubilized to give a concentration of 300 mm at near physiological pH, histidine and proline caused a complete hemolysis of newborn calf but not of adult cow red cells within 20 to 30 minutes at 38 degrees C. While hydroxyproline, valine, and serine resulted in a partial lysis of calf cells, threonine, glutamine, and glycine were ineffective. In this communication, emphasis has been focused on the mode of the lytic process by histidine which was found to be affected by several governing parameters including the pH, temperature and the extracellular salts in the solution. Unlike human red cells suspended in isotonic histidine, both calf and cow cells lost little Na and K ions. In the presence of 300 mm histidine, both calf and cow cells displayed an instantaneous uptake of histidine amounting to 20 to 45 mumoles/ml RBC followed by a slow influx rate of 0.25 to 0.5 mumoles/ml RBC X min. The extent to which histidine entry was allowed by the cell was counterbalanced by Cl- efflux, resulting in little change in cell volume prior to hemolysis. Moreover, histidine-induced hemolysis can be prevented by 1 mm or lower PCMBS without a discernible effect on histidine influx suggesting a possible membrane lesion or damage at the outer surface of the cell. Hemolysis induced by histidine decreased substantially when a calf reached two months of age at which time the red cells containing the fetal hemoglobin are virtually depleted. The results of hemoglobin electrophoresis obtained during this postnatal period revealed that those cells resistant to histidine hemolysis almost invariably contain the adult type hemoglobin suggesting a selective, specific action of the amino acids on the fetal cells.

Biochemical characterization of density-separated human erythrocytes

A simple, reproducible method for the separation of human erythrocytes, described recently (Murphy, J. R. (1973) J. Lab. Clin. Med. 82, 334-341) has been utilized for the purpose of obtaining a wide range of biochemical data on these cells. Using phthalate ester density centrifugation of the fractions obtained by Murphy's method, we established that the cells were separated exclusively on the basis of their densities. Data on a wide range of biochemical and hematological parameters, when compared with previously reported density separation procedures showed that this simple technique can be used to fractionate the cells according to their densities (age) in their own plasma. Cells of increasing density consistently and reproducibly exhibited an increase in hemoglobin concentration, a moderate elevation in Na+ and a decrease in the following: K+, acetylcholinesterase, sialic acid, membrane protein, 2,3-diphosphoglycerate, ATP, cholesterol, phospholipid, mean corpuscular volume and critical hemolytic volume, However, no change in mean corpuscular hemoglobin was evident. The observed differences were not artifacts of the centrifugation process. This was determined in recentrifuged top fractions from which new top and bottom cells were obtained. The latter cells resembled the top fraction from which they were obtained, rather than the original bottom fraction. Whereas the parameters mentioned above exhibited consistency and reproducibility, such was not the case with the ATPase values. Depending on the cell density group examined and/or buffer as well as other conditions, significant variability in the activity levels of the ouabain sensitive, as well as the Ca2+ -stimulated ATPase, was observed. Use of these enzyme activities as indicators of cell age must be viewed with caution.