Effects of carbon dioxide and pH variations in vitro on blood respiratory functions, red blood cell volume, transmembrane pH gradients, and sickling in sickle cell anemia
An examination was made of the O/sub 2/ affinity, Bohr effect, transmembrane pH gradient, mean cell hemoglobin concentration, and red blood cell sickling at half O/sub 2/ saturation in whole sickle cell (SS) and normal (AA) blood during CO/sub 2/ titration and acid-base titration at three Pco/sub 2/ levels, 10, 40, and 80 mm Hg. The CO/sub 2/-induced Bohr effect of SS blood was considerably larger than normal (maximum, 0.91, referred to cell pH) and similar to that found with acid-base titration at Pco/sub 2/ of 40. In contrast to AA blood, SS blood showed an increased O/sub 2/ affinity when Pco/sub 2/ was raised from 40 to 80, and at half O/sub 2/ saturation showed biphasic or sigmoid Bohr curves, a fall in transmembrane pH gradient with rising Pco/sub 2/, and an absence of the normal cell volume increase at low pH and Pco/sub 2/. Sickling of SS cells at half O/sub 2/ saturation was partly inhibited by increasing Pc/sub 2/, particularly in the higher pH ranges. These complex differences in the behavior of SS blood are interpreted in terms of the balancing of several effects: the lowering of hemoglobin O/sub 2/-affinity by polymerization, low pH and increased CO/sub 2/ binding, inhibition of hemoglobin S polymerization by CO/sub 2/ binding to ..beta../sup s/-chain amino termini, differences between hemoglobin S and A in competitive binding of CO/sub 2/ and 2,3-diphosphoglycerate at different pH levels, and an increased net negative charge exhibited by intracellular deoxyhemoglobin S polymers. From a clinical standpoint, in the absence of hypoxia or acidosis, an increased blood Pco/sub 2/ might have a beneficial effect by inhibiting red blood cell sickling, whereas a metabolic acidosis, with low blood pH and Pco/sub 2/, would be very hazardous.
- Research Organization:
- Albert Einstein Coll. of Medicine, Bronx, NY
- OSTI ID:
- 6166141
- Journal Information:
- J. Lab. Clin. Med.; (United States), Vol. 104:2
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
CARBON DIOXIDE
BIOLOGICAL EFFECTS
ERYTHROCYTES
MORPHOLOGY
PH VALUE
VARIATIONS
SICKLE CELL ANEMIA
BLOOD
IN VITRO
ANEMIAS
BIOLOGICAL MATERIALS
BLOOD CELLS
BODY FLUIDS
CARBON COMPOUNDS
CARBON OXIDES
CHALCOGENIDES
DISEASES
HEMIC DISEASES
MATERIALS
OXIDES
OXYGEN COMPOUNDS
SYMPTOMS
560301* - Chemicals Metabolism & Toxicology- Cells- (-1987)