Erythrocyte Hb-S Concentration AN IMPORTANT FACTOR IN THE LOW OXYGEN AFFINITY OF BLOOD IN SICKLE CELL ANEMIA

Seakins, M.; Gibbs, W. N.; Milner, Paul F.; Bertles, John F.

doi:10.1172/jci107199

Cited by 171 publications

(84 citation statements)

References 44 publications

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“…Separation of oxyhemoglobin S was carried out by DEAEcellulose chromatography with minor variations of the method described by Huisman and [27][28][29]1974. 4864 molecular weight of 16,000 g/mole of heme.…”

Section: Methodsmentioning

confidence: 99%

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Kinetics and Mechanism of Deoxyhemoglobin S Gelation: A New Approach to Understanding Sickle Cell Disease

Hofrichter

Ross

Eaton

1974

Proc. Natl. Acad. Sci. U.S.A.

486

331

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We report the results of a kinetic investigation on the gelation of purified deoxyhemoglobin S. Gelation was induced by raising the temperature and was monitored by measuring both the heat absorbed, with a microcalorimeter, and the appearance of linear birefringence, with a microspectrophotometer. The kinetics are unusual. Prior to the onset of gelation there is a delay period, followed by a sigmoidal progress curve. The delay time is formally dependent on approximately the 30th power of the deoxyhemoglobin S concentration; a decrease in concentration from 23 to 22 g/dl increases the delay time by a factor of four. It is also extremely temperature dependent; a 1C temperature rise in the range 20-30'C almost halves the delay time. From these results we conclude that the initial rate is controlled by the nucleation of individual fibers. We present a kinetic model that accounts for the concentration, temperature, and time dependence of the initial phase of the gelation reaction. Extrapolation of our data to physiological conditions predicts that changes in intracellular hemoglobin concentration and oxygen saturation, realizable in vivo, produce enormous changes in the delay time. The range of delay times spans both the mean capillary transit and total circulation times. This result points to the delay time as an extremely important variable in determining the course of sickle cell disease, and suggests a new approach to therapy.Hemoglobin S in concentrated solutions aggregates to form a highly viscous material, referred to as a gel. It is the formation of this gel that rigidifies and distorts deoxygenated erythrocytes of patients with sickle cell anemia. Considerable new insight into the structure and equilibrium behavior of this system has been gained through recent electron microscope (1), x-ray diffraction (1, 2), optical (3), solubility (4), sedimentation (5-7), and theoretical (8, 9) studies. The gel may be tentatively described as consisting of two phases in reversible equilibrium: a liquid phase containing mainly monomeric (molecular weight of 64,000) hemoglobin and a solid phase containing polymeric hemoglobin in the form of bundles of long straight fibers (compare ref. 8). The-solid phase, which exhibits optical birefringence and other properties of a liquid crystal, is favored by low oxygen concentrations and high temperatures.Much less is known about gelation kinetics. The rate of gelation of deoxyhemoglobin S at a fixed temperature T may be measured in two ways:(1) oxyHbS (T)In the first experiment gelation is induced by removing oxygen from an oxyhemoglobin S solution. In the second, gelation is induced by raising the temperature of an already deoxygenated hemoglobin S solution from 0C, where it is a nonbirefringent liquid, to the higher temperature T. Although the first experiment may be considered more relevant to the in vivo sickling process, the two experiments should give identical results if the deoxygenation and temperature change are both fast when compared to the rate of gelation. Neit...

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Section: Methodsmentioning

confidence: 99%

“…The delay times, estimated as a function of total hemoglobin S concentration (28) and the percent saturation with oxygen' at 370C are shown in Fig. 5 in the form of a map.…”

Section: Methodsmentioning

confidence: 99%

Kinetics and Mechanism of Deoxyhemoglobin S Gelation: A New Approach to Understanding Sickle Cell Disease

Hofrichter

Ross

Eaton

1974

Proc. Natl. Acad. Sci. U.S.A.

486

331

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“…Deletion of one of a pair of closely linked athalassemia genes (heterozygous a þ -thalassemia) in SS disease tends to lower the mean cell hemoglobin concentration (MCHC), which as a determinant of HbS polymerization (Seakins et al 1973), is likely to reduce intravascular sickling. Deletion of both of the closely linked a-thalassemia genes (homozygous a þ -thalassemia) has an even greater effect in lowering the MCHC but any consequent reduction in sickling may be offset by an increase in total hemoglobin.…”

Section: A-thalassemiamentioning

confidence: 99%

The Natural History of Sickle Cell Disease

Serjeant¹

2013

Cold Spring Harbor Perspectives in Medicine

216

159

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“…In sickle cell anaemia, the single mutation on the b-globin chain confers a much lower solubility on haemoglobin (Hb) S than HbA under the same oxygen tension, with a significant decrease in oxygen affinity (Becklake et al, 1955;Seakins et al, 1973). Sickle cells are consequently largely deoxygenated at the oxygen tension in the capillary circulation.…”

mentioning

confidence: 99%

Do HbSS erythrocytes lose KCl in physiological conditions?

Dormandy¹,

Ellory²

1997

Br J Haematol

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Summary. KCl cotransporter activity in sickle (HbSS) red blood cells (RBCs) was measured in cells suspended in 'simple' physiological saline, saline augmented with inorganic salts, and autologous plasma. Our results showed that the transporter was only functioning at 20% of the level of cells in saline when cells were resuspended in autologous plasma. Kinetic analysis of the data showed that plasma decreased both V max and K m for K + of the transporter. The plasma factor(s) responsible was heat-stable and dialysable (i.e. size < 10 kD).Adding magnesium, calcium, inorganic phosphate or bicarbonate to 'simple' saline to mimic the effect of plasma revealed that Mg 2+ and Ca 2+ had no significant effect at physiological concentrations. P i was not effective at 1 . 1 mM , but did inhibit significantly (42Ϯ2%Þ at 5 . 6 mM . HCO ¹ 3 had a major inhibitory effect on K + influx when added to saline, and was identified as the principal candidate for the plasma effect.We suggest bicarbonate may play a significant role in modifying KCl cotransport, and hence HbSS cell volume in vivo. It acts by altering the set point of the transporter via the signalling systems involved in its regulation.

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Erythrocyte Hb-S Concentration AN IMPORTANT FACTOR IN THE LOW OXYGEN AFFINITY OF BLOOD IN SICKLE CELL ANEMIA

Cited by 171 publications

References 44 publications

Kinetics and Mechanism of Deoxyhemoglobin S Gelation: A New Approach to Understanding Sickle Cell Disease

Kinetics and Mechanism of Deoxyhemoglobin S Gelation: A New Approach to Understanding Sickle Cell Disease

The Natural History of Sickle Cell Disease

Do HbSS erythrocytes lose KCl in physiological conditions?

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