Metabolic dependence of the critical hemolytic volume of human erythrocytes: relationship to osmotic fragility and autohemolysis in hereditary spherocytosis and normal red cells

Effects of nickel chloride on the erythrocytes and erythrocyte immune adherence function in broilers

This study was conducted to investigate the immune adherence function of erythrocytes and erythrocyte induced by dietary nickel chloride (NiCl2) in broilers fed on a control diet and three experimental diets supplemented with 300, 600, and 900 mg/kg NiCl2 for 42 days. Blood samples were collected from five broilers in each group at 14, 28, and 42 days of age. Changes of erythrocyte parameters showed that total erythrocyte count (TEC), hemoglobin (Hb) contents, and packed cell volume (PCV) were significantly lower (p < 0.05 or p < 0.01) and erythrocyte osmotic fragility (EOF) was higher (p < 0.05 or p < 0.01) in the 600 and 900 mg/kg groups at 28 and 42 days of age than those in the control group, and the sodium-potassium adenosine triphosphatase (Na(+)/K(+)-ATPase) and calcium adenosine triphosphatase (Ca(2+)-ATPase) activities were significantly decreased (p < 0.05 or p < 0.01) in the NiCl2-treated groups. The results of erythrocyte immune adherence function indicated that erythrocyte C3b receptor rosette rate (E-C3bRR) was significantly decreased (p < 0.05 or p < 0.01) in the 600 and 900 mg/kg groups and in the 300 mg/kg group at 42 days of age, whereas the erythrocyte immune complex rosette rate (E-ICRR) was markedly increased (p < 0.05 or p < 0.01) in the 300, 600, and 900 mg/kg groups at 28 and 42 days of age. It was concluded that dietary NiCl2 in excess of 300 mg/kg caused anemia and impaired the erythrocytic integrity, erythrocytic ability to transport oxygen, and erythrocyte immune adherence function in broilers. Impairment of the erythrocytes and erythrocyte immune adherence function was one of main effect mechanisms of NiCl2 on the blood function.

Effects of high dietary fluorine on erythrocytes and erythrocyte immune adherence function in broiler chickens

Fluoride can exert toxic effects on soft tissues, giving rise to a broad array of symptoms and pathological changes. The aim of this study was to investigate on erythrocytes and erythrocyte immune adherence function in broiler chickens fed with high fluorine (F) diets by measuring the total erythrocyte count (TEC), the contents of hemoglobin (Hb), packed cell volumn (PCV), erythrocyte osmotic fragility (EOF), erythrocyte C3b receptor rosette rate (E-C3bRR), and erythrocyte immune complex rosette rate (E-ICRR). A total of 280 1-day-old healthy avian broiler chickens were randomly allotted into four equal groups of 70 birds each and fed with a corn-soybean basal diet containing 22.6 mg F/kg (control group) or same basal diets supplemented with 400, 800, and 1,200 mg F/kg (high F groups I, II, and III) in the form of sodium fluoride for 42 days. Blood samples were collected for the abovementioned parameters analysis at 14, 28, and 42 days of age during the experiment. The experimental results indicated that TEC, Hb, and PCV were significantly lower (p < 0.05 or p < 0.01), and EOF was higher (p < 0.05 or p < 0.01) in the high F groups II and III than that in the control group from 14 to 42 days of age. The E-C3bRR was significantly decreased (p < 0.01) in the three high F groups, whereas the E-ICRR was markedly increased (p < 0.01) in the high F groups II and III from 14 to 42 days of age. It was concluded that dietary F in the range of 800 to 1, 200 mg/kg could significantly cause anemia and impair the integrity of erythrocyte membrane, the transport capacity of oxygen and carbon dioxide, and erythrocyte immune adherence function in broiler chickens.

Amphiphile-induced vesiculation in aged hereditary spherocytosis erythrocytes indicates normal membrane stability properties under non-starving conditions

Aged HS erythrocytes with a defined primary defect in band 3 protein or ankyrin were incubated with amphiphiles (detergents) at sublytic concentrations (37 C, 60 min) or glucose-starved (37 C, 24 h). In line with previous studies, the release of AChE (exovesicles) from HS erythrocytes during glucose-starvation was significantly higher (11%) compared to that from control erythrocytes (1%). Control and HS cells responded, however, similarly to amphiphile-treatment (non-starving conditions). Amphiphiles induced similar types of shape alterations and a similar amount of AChE release (14-15%). Furthermore, the size and shape of amphiphile-induced exo- and endovesicles released from control and HS erythrocytes were similar. The results suggest that the stability properties of the membrane are not seriously disturbed in aged HS erythrocytes under non-starving conditions.

The reduction of nitroblue tetrazolium by red blood cells: a measure of Red Cell membrane antioxidant capacity and hemoglobin-membrane binding sites

The reduction of nitroblue tetrazolium (NBT) with intact Red Blood Cells (RBCs) is biphasic with an initial rapid reduction followed by a slower second phase. This biphasic kinetics has been explained with the initial rapid phase attributed to antioxidants in the red cell which reduce membrane bound NBT and the slower phase associated with the reaction of NBT with membrane bound hemoglobin. This model has been confirmed by a utilization of a number of red cell modifications which either increase the red cell antioxidants (vitamin C and vitamin E) or damage the red cell membrane (cumene hydroperoxide and N-ethylmaleimide). The utilization of this assay for human blood samples was investigated by studying a series of 20 human subjects ranging between 34 and 87 years of age. It was possible to fit all of these samples with two adjustable parameters which reflect the red cell membrane antioxidant capacity (x) and the hemoglobin membrane interactions (m). The antioxidant capacity shows a significant (p < .002; R = -.67) decrease with age. This finding is consistent with a decrease in the level of antioxidants in aged subjects. In addition, the number of hemoglobin membrane sites are negatively correlated with the antioxidant capacity (p < .02; R = -.52) suggesting that the oxidative stress associated with reduced antioxidants results in increased hemoglobin-membrane interactions.

Red cell abnormalities in hereditary spherocytosis: relevance to diagnosis and understanding of the variable expression of clinical severity

Marked variations in the clinical manifestations of hereditary spherocytosis (HS) have long been recognized. However, neither the molecular nor the cellular basis for this variable expression has been fully delineated. To better define the cellular basis for variable expression of the disease, we evaluated the pathobiology of red cells in a large series of 55 non-splenectomized and 31 splenectomized patients with HS. Red cell membrane surface area, surface area-to-volume ratio, cell volume, and state of cell hydration were quantitated. We found that decreased membrane surface area was a distinguishing feature of red cells in all patients studied, whereas decreased surface area-to-volume ratio as reflected by increased osmotic fragility was noted in only 66% of the non-splenectomized patients. In terms of red cell indexes, the percentage of microcytes was not a good discriminator of HS phenotype but was the best indicator of the severity of the disease. In contrast, the presence of increased numbers of hyperdense cells was an effective discriminating feature of the HS phenotype but a poor indicator of disease severity. These findings have enabled us to define the dominant cellular changes that account for the variable clinical severity of this common red cell membrane disorder and have allowed development of improved approaches for its diagnosis.

Effects of preparative procedures on the volume and content of resealed red cell ghosts

The effects of variations in preparative procedures on the volume and content of resealed red cell ghosts have been investigated. Following hypotonic lysis at 0 degrees C, and after a variable delay time (td), concentrated buffer was added to restore isotonicity; resealing was then induced by incubation at 37 degrees C for one hour. Using this procedure, both the resealed ghost volume and the residual hemoglobin (Hb) content decreased for increasing td. If ghosts were maintained at 0 degree C (i.e., no 37 degrees C incubation), they remained nearly spherical until isotonicity was restored. Their volume then fell abruptly, but subsequently increased toward an intermediate level. The fall in volume was greater and the final level achieved was smaller for longer delay times. At 0 degree C, return to isotonicity also halted the otherwise gradual loss of residual Hb from unsealed ghosts. In addition, ghosts with internal osmolality of 40 to 300 mosmol/kg were prepared by adding different amounts of concentrated buffer before resealing for one hour at 37 degrees C. Under these conditions, the final ghost volume was inversely related to the resealing osmolality (i.e., lower osmolality yielded a larger volume). Ghost volume also increased, along with Hb content, if the quantity or concentration of the red cell suspension added to the lysing medium was increased. We conclude that resealed ghost volume is influenced by the ratio of lysate to resealing medium osmolality and by the colloid osmotic pressure of the residual ghost Hb. These data indicate methods by which ghosts with desired characteristics can be prepared, and have potential application for studies of ghost mechanical and biophysical behavior.

In vivo shedding of apical plasma membrane in the thyroid follicle cells of the mouse

Clusters of luminal dense bodies, limited by a triple-layered membrane, were found in all follicle lumina in thyroid glands of mice. After thyroxine treatment the number of luminal dense bodies increased, especially in the periphery of the lumen, where the intraluminal bodies often displayed a striking resemblance to microvilli. In hyperplastic goiters, obtained by feeding mice with propylthiouracil, luminal dense bodies were replaced by intraluminal vesicles. During goiter involution the vesicles were gradually replaced by luminal dense bodies; the presence of intermediate forms suggests that vesicles and dense bodies are basically the same formations. Luminal dense bodies were observed in colloid droplets indicating their removal by endocytosis. As demonstrated by electron-microscopic cytochemistry, luminal dense bodies contain a membrane-bound peroxidase, and electron-microscopic autoradiography after administration of 125I indicate that they possess an iodinating capacity. Our observations on mouse thyroid glands suggest that the luminal dense bodies, which appear as vesicles in hyperplastic glands, are formed by shedding of the apical plasma membrane of the follicle cell. The shedding process might be of importance for the turnover of plasma-membrane material.

Abrogation of calcium exclusion by erythrocytes under hypotonic stress

Normal human erythrocytes in isotonic suspension maintain a high gradient of calcium ion concentration across the membrane, with the cytosol [Ca2+] several orders of magnitude below plasma concentration. Despite the high degree of exclusion maintained against the entry of Ca2+, the osmotic resistance of red cells in hypotonic saline is significantly augmented by the presence in the medium of Ca2+ in concentrations greater than 0.07 mmol/l. Resistive particle spectroscopy showed this to occur without alteration of the mean critical haemolytic volume; furthermore, in the presence of Ca2+ there was a reduction in cell volume at prolytic osmolalities when compared with cells in calcium-free sodium chloride solutions. This is shown to be due to augmentation of the prolytic loss of K+ in the presence of Ca2+ through calcium-sensitive channels, and indicates that the pathway for passive K+ efflux uncovered in the prolytic state is indistinguishable from that of normal passive K+ diffusion. It is also demonstrated that the prolytic red cell membrane is permeable to Ca2+ and admits the divalent cation to the inner aspect of the plasma membrane. These changes are comparable to those of cells prior to haemolysis in vivo, as in the irreversibly sickled cell, and are therefore not specific to the latter condition.

Osmotic hemolysis and fragility. A new model based on membrane disruption, and a potential clinical test

Red cell osmotic hemolysis has traditionally been defined by the loss of hemoglobin, in response to reduced osmotic pressure, as measured spectroscopically. Previous work from this laboratory using resistive pulse spectroscopy (RPS) has shown that in a mixed population of hemolyzing cells, ghosts can be detected as being more deformable, and hence appearing distinctly smaller, than the remaining intact cells. Other researchers using similar methods have reported detection of ghosts as apparently smaller objects, resulting from their greater sensitivity to dielectric breakdown. We now confirm both of these results, and demonstrate by kinetic studies that changes which occur in the rheological and electrical properties of ghosts are independent phenomena. We include in our analysis the explicit calculation of ghost and intact spherocyte resistivity after dielectric breakdown. The two different characterizations for ghosts are integrated into a proposed model of osmotic hemolysis based on known red blood cell membrane and cytoplasmic properties. This work provides both a theoretical and a practical foundation for RPS-based measures of osmotic fragility, including a potential new clinical test, measures which provides very early detection of the ultimate fate of osmotically stressed red cells.

The size of erythrocyte ghosts

The volume of resealed erythrocyte ghosts formed during hypotonic hemolysis of normal human erythrocytes was measured by means of a continuous mean corpuscular volume analyzer. The final volume of resealed ghosts was 140.6 +/- 15.2 fl. Strong correlations exist between the volume of ghosts and the initial mean corpuscular volume and mean corpuscular hemoglobin of the erythrocyte, and between the enlargement ratio and the mean corpuscular volume or mean corpuscular hemoglobin of the erythrocyte.

Effect of ouabain on osmotic resistance and monovalent cation transport of red cells in hereditary spherocytosis

The effect of ouabain on the osmotic resistance of red cells from 17 splenectomized patients with congenital or hereditary spherocytosis (HS), from 5 of their relatives suspected of having a subclinical form of the disease and from unsplenectomized and splenectomized normal controls was studied. In red cells from the HS patients and the splenectomized controls a small ouabain-induced decrease in osmotic resistance was seen, whereas in the unsplenectomized controls no such change was observed. The osmotic resistance of red cells from the 5 relatives, on the other hand, was significantly decreased by ouabain. The usefulness of ouabain in unmasking HS in its subclinical form was further tested by studying monovalent cation influx into red cells. The active influx of 86Rb+ into red cells from HS suffers was significantly increased. A similar degree of ouabain-induced inhibition of 86Rb+ transport was seen in all groups studied. The passive influx of 22Na+, which was also increased in HS red cells, was not affected by ouabain in any of the four groups.

Red cell membrane protein phosphorylation in hemolytic anemias and muscular dystrophies

We review our current understanding of membrane phosphorylation in normal and abnormal erythrocytes. The major phosphoproteins in red blood cell (RBC) membranes are spectrin (band 2), bands 3, 2.1, and 4.5, and glycophorin A. At least two protein kinases can be distinguished on the basis of their stimulation by cyclic AMP and salt; they are present both in the membrane and in the cytosol. Analysis of the conflicting data on endogenous membrane-protein phosphorylation in abnormal RBCs indicates a considerable variability of phosphorylation rates which largely depends on the manner of preparation of ghosts and enzyme assay conditions. This variability reflects differences in the partitioning of protein kinases between the membrane and cytosol, the specificity and accessibility of membrane-protein substrates, and reaction kinetics. We select examples of data from several hemolytic anemias to illustrate that precautions are needed to interpret abnormalities of membrane-protein phosphorylation properly; we discuss possible new methodological approaches.

Cross-linking of membrane proteins of metabolically-depleted and calcium-loaded erythrocytes

The membranes of erythrocytes undergoing metabolic depletion or an influx of calcium undergo several changes in structure and function. In erythrocytes incubated without substrate we find extensive cross-linking of membrane proteins by disulphide bonding occurring after 24--48 h, involving all major membrane proteins as well as haemoglobin. Aggregates of mol wt 40 x 10(6) or greater are formed. These changes are partially reversible by repletion with adenosine. Rapid introduction of calcium (intracellular concentrations approximately 0.6 mM) into metabolically replete erythrocytes with the ionophore A23187 results in transglutaminase-dependent cross-linking of membrane proteins. Cellular calcium concentrations of approximately 0.3 mM have no cross-linking effect. Cells undergoing metabolic depletion show a progressive loss of transglutaminase activity to undetectable levels at 12 h, so that influx of calcium into such cells cannot cause cross-linking by a transglutaminase-mediated reaction. These studies suggest that the metabolic state of the cell and the rate and degree of calcium influx into erythrocytes are critical factors in determining the type of membrane protein cross-linkage.

Specific calcium antagonists in the treatment of peripheral vascular disease

The antivasoconstrictor activity of the drugs cinnarizine and flunarizine is considered in relation to their inhibitory action on calcium ion flux mechanisms. Their clinical efficacy in peripheral vascular disease is reviewed, and the possible mode of action of the two drugs is discussed in relation to their described pharmacologic effects.

Hereditary spherocytosis revisited. Eighth annual Paul M. Aggeler Memorial Lecture. Delivered October 25, 1977, San Francisco General Hospital Medical Center

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Membrane proteins of incubated erythrocytes: effect of sulphydryl inhibition

Incubation of erythrocytes with various sulphydryl inhibitors for 24 h leads to an accumulation in isolated membranes of globin as well as an unidentified polypeptide of apparent molecular weight 24 000 on polyacrylamide gel electrophoresis. Accumulation of both these components does not appear to be directly related to erythrocyte adenosine triphosphate and reduced glutathione levels. The 24 000 molecular weight polypeptide is probably derived from the erythrocyte cytosol, as determined by polyacrylamide gel electrophoresis of the non-haemoglobin proteins of the cytosol. Together with globin it forms an integral part of the 'spectrin-actin lattice' of sulphydryl-inhibited erythrocytes, as both these components can be detected, together with spectrin and actin, after extraction of such membranes by Triton X-100. We postulate that this leads to inherent damage and distortion to the membranes of such erythrocytes.

Rearrangements of integral membrane components during in vitro aging of sheep erythrocyte membranes

In vitro aged sheep erythrocytes and sheep erythrocyte ghosts spontaneously release vesicles that consist of long protrusions affixed to flattened headlike structures. The intramembranous particles seen on the protoplasmic face of freeze fracture electron micrographs of vesicle protrusions are arranged in paired particle rows. On the equivalent fracture face of headlike structures, the particle density is low; if particles are present, they are clustered along the rim of the flattened headlike structure and at the junction with the protrusion. The released vesicles are depleted of the intramembranous particles seen on the exoplasmic face of ghost but retain almost exclusively particles of the protoplasmic face. Correspondingly, the exoplasmic face of ghosts that have released vesicles reveals a 28 percent higher density of intramembranous particles than that of fresh ghosts. Purified vesicles are depleted of spectrin but retain integral membrane proteins, with one of an apparent mol wt of 160,000 accounting for nearly 50 percent of the total protein (Lutz, H.U.,R. Barber, and R.F. McGuire. 1976. J. Biol. Chem. 251:3500-3510). When vesicles are modified with the cleavable cross-linking reagent [(35)S]dithiobis (succinimidyl propionate)at 0 degrees C, the 160,000 mol wt protein is rapidly converted to disulfide-linked dimers and higher oligomers. Exposure of intact ghosts to the reagent in the same way fails to yield equivalent polymers. A comparison of the morphological and biochemical aspects of ghosts and vesicles suggest that a marked rearrangement of membrane proteins accompanies the supramolecular redistribution of intramembranous particles during spontaneous vesiculation. The results also suggest that the paired particles of the protoplasmic face of vesicle protrusions are arranged in paired helices and contain the 160,000 mol wt protein as dimers.

Release of spectrin-free vesicles from human erythrocytes during ATP depletion. I. Characterization of spectrin-free vesicles

Human erythrocytes incubated without glucose at 37 degrees C (in vitro aging) release spectrin-free vesicles after 12 or more hours. The release of vesicles is dependent upon ATP depletion. If the endogenous level of ATP is maintained, vesicle release is completely inhibited up to 54 h. Vesicle release is independent of hemolysis because in vitro aged cells and cells that maintain their ATP levels lose identical amounts of hemoglobin up to 45 h. 93 percent of all membrane particles released constitute a uniform population of spheres with a diameter of 185 +/- 23nm. These vesicles are of slightly varying densities due to varying contents of hemoglobin. Vesicles contain half the amount of membrane protein that is found in intact membranes when referred to the content of phospholipids phosphorus. This is primarily due to the absence of spectrin. However, their content of protein component III, glycophorin, and cholesterol remains the same as in intact membranes. Thus, the major integral membrane proteins are present in vesicles in similar quantities were surface area as in cells except for the enzyme acetylcholinesterase that is enriched up to twofold. The phospholipids composition of these vesicles is representative of the intact membrane except that the amount of phosphatidic acid is 10-fold higher and the amount of phosphatidylethanolamine is slightly lower than in erythrocytes. These results suggest a selective release of membrane domains that lack peripheral membrane proteins and are enriched in acetylcholinesterase. This release of spectrin-free vesicles from cells aged in vitro could represent an acceleration of the physiological aging process.

Physical and chemical changes of ACD-preserved blood: a comparison of blood in glass bottles and plastic bags

ACD blood was preserved in glass bottles with or without aeration and in plastic bags in air or nitrogen gas at 4.5 degrees C. The blood was examined for physical and chemical changes of erythrocyte membrane resistance, hemoglobin in the plasma, the viscosity of the blood, pH of plasma, and ATP and 2,3-DPG content of erythrocytes. The blood preserved in plastic bags showed less changes than blood in glass bottles. The presence of air or nitrogen gas in blood seems to increase the pH perhaps by elimination of carbon dioxide (CO2) which in turn causes the different rates of glycolysis in the erythrocytes.

Hemolytic anemias. Failure of the red cell membrane

The normal erythrocyte membrane is composed of nearly equivalent amounts of lipid and protein. The lipid portion of the membrane has been well studied. Even though de novo synthesis of lipid does not occur in human red cells, many biochemical pathways exist which facilitate detoxification of lipid breakdown products and lipid renewal. Rare defects in these processes are associated with hemolytic disorders. Recent studies have revealed that the membrane proteins are diverse and suggest that protein dysfunction may also account for clinical disease. Protein and lipid are entwined in a physicochemical relationship which is probably best depicted by the classic lipid bilayer with interspersed proteins in both the inner and outer surfaces and also spanning the bilayer. Membrane failure results in hemolytic anemia. This failure can be intrinsic, caused by abnormal lipid or protein constituents; or extrinsic, with a normal membrane being unable to counteract physical, chemical or immunologic stress. Clinical examples of membrane failure and hemolytic anemia can be separated into three groups according to the predominant mechanism of the hemolysis: fragmentation, whole-cell lysis, and filtration and entrapment. Although these mechanisms can act separately or in concert, the final hemolytic destruction of the cell can usually be traced to a failure of membrane function.

Observations on the in vivo aging of red cells in the rat

Aging of rat erythrocytes was studied in vivo by two experimental models. In the first, a single cohort of erythrocytes labelled with radioiron was followed; in the second, sequential hypertransfusions were employed to obtain a defined red cell population, which was continuously transferred from host to host. The results are compatible with a normal red cell life span of about 60 days and with sequestration of senescent erythrocytes in the spleen and in the liver. Red cell aging was associated with a decline in cell volume, haemoglobin, G6PD and ATP content. There were no measureable changes in osmotic fragility. Thus, changes in osmotic resistance do not appear to be critical factors limiting the life span of circulating erythrocytes in the rat.

Drug-induced erythrocyte membrane internalization

In vitro erythrocyte membrane internalization, resulting in the formation of membrane-lined vacuoles, can be quantified by a radioisotopic method. A complex of (37)Co-labeled vitamin B(12) and its plasma protein binders is first adsorbed to the cell surface, and after vacuoles are formed, the noninternalized label is removed by washing and trypsin treatment. The residual radioactivity represents trapped label and can be used to measure the extent of membrane internalization. Using this method, it was found that in addition to primaquine, a group of membrane-active drugs, specifically hydrocortisone, vinblastine, and chlorpromazine can induce membrane internalization in erythrocytes. This is a metabolic process dependent on drug concentration, temperature, and pH. Vacuole formation by all agents tested can be blocked by prior depletion of endogenous substrates or by poisoning the erythrocytes with sodium fluoride and sulfhydryl blocking agents. This phenomenon resembles in some respects the previously reported membrane internalization of energized erythrocyte ghosts. It is suggested that membrane internalization is dependent on an ATP-energized state and is influenced by the balance between the concentrations of magnesium and calcium in the membrane. This study provides a basis for proposing a unifying concept of the action of some membrane-active drugs, and for considering the role of erythrocyte membrane internalization in pathophysiologic events.

The effects of cyanate in vitro on red blood cell metabolism and function in sickle cell anemia

Cyanate, which is in equilibrium with urea, combines with the alpha-amino group of the aminoterminal valine of hemoglobin in an irreversible, specific carbamylation reaction. Partial carbamylation (0.72 residues/hemoglobin tetramer) as determined by cyanate-(14)C incorporation or hydantoin analysis diminishes the in vitro sickling phenomenon. Since cyanate may react not only with hemoglobin but also with functional groups of other red blood cell proteins, the in vitro effect of cyanate was studied on sickle cells. Cells were incubated with 10 mM KCl (control) or 10 mM KNCO (carbamylated) for 1 hr, washed, and resuspended in autologous plasma. Glycolysis, ATP and 2,3-diphosphoglyceric acid (DPG) stability, autohemolysis, and osmotic fragility were not affected by carbamylation. Potassium loss in carbamylated cells (2.8 mmol/liter) was less than in control cells (9.0 mmol/liter). Pyruvate kinase activity of carbamylated cells was decreased ( approximately 25%) but the activities of other glycolytic enzymes were similar to those of control cells. Oxygen affinity of carbamylated sickle, normal, and DPG-depleted normal cells increased, and was a sensitive index of the degree and duration of reaction with cyanate. The reactivity of carbamylated cells to DPG was similar to control cells. DPG-depleted carbamylated cells regenerated DPG and increased the P(50) when incubated with pyruvate, inosine, and phosphate. The Bohr effect of normal and of sickle cells was not affected (Deltalog P(50)/Delta pH=-0.48 and -0.53, respectively) after carbamylation. The reserve buffering capacity of plasma offset the slightly diminished ( approximately 15%) CO(2) capacity of carbamylated cells so that whole blood CO(2) capacity, pH, and P(CO2) were normal. These studies provide further support for the potential clinical use of cyanate in treating and preventing the anemia and painful crises of sickle cell disease.

The erythrocyte ghost is a perfect osmometer

The osmotic swelling of intact erythrocytes in hypotonic solutions was measured using microhematocrit tubes, Van Allen tubes, and a calibrated Coulter counter. In agreement with earlier workers the intact cells did not behave as perfect osmometers, the cells swelling less than predicted by the Boyle-van't Hoff law. Erythrocyte ghosts were prepared from fresh intact erythrocytes by one-step hemolysis in 0.25% NaCl at an extremely dilute concentration of cells and the membranes were sealed at 37 degrees . The ghosts were mixed with NaCl solutions of different osmolarities and the MCV (mean cell volume) of the shrunken cells immediately monitored by a calibrated Coulter counter. It was found that the MCV values of the shrunken ghosts were accurately predicted by the Boyle-van't Hoff law. These results indicate that these erythrocyte ghosts behaved as perfect osmometers.