Modulation of red blood cell oxygen affinity with a novel allosteric modifier of hemoglobin is additive to the Bohr effect

Pregnancy in Crotalus viridis oreganus is associated with an increase in the nucleoside triphosphate (NTP) concentration and a concomitant decrease in the oxygen affinity of the adult red blood cell. However, although the red blood cells of non-pregnant adults and fetuses have indistinguishable NTP concentrations, they have different oxygen affinities. Therefore, red blood cell NTP concentrations alone cannot account for the oxygen-affinity difference between fetal and maternal red blood cells. Hemoglobins from adult and fetal snakes had similar intrinsic oxygen affinities; however, adult hemoglobin was more responsive to organic phosphate modulation compared with fetal hemoglobin. Structural differences, indicated by native gel electrophoresis and electrophoresis of the globins under denaturing conditions at high pH, corroborated functional differences of hemoglobins from fetus and adult. Therefore, the biochemical basis for the oxygen-affinity difference between maternal and fetal red blood cells in this rattlesnake appears to be unique. It appears to be caused by a functionally distinct fetal hemoglobin and the pregnancy-associated rise in red blood cell NTP levels in the mother.

Download Full-text

Effect of haemoglobin concentration on the oxygen affinity of intact lamprey erythrocytes

Journal of Experimental Biology ◽

10.1242/jeb.198.11.2393 ◽

1995 ◽

Vol 198 (11) ◽

pp. 2393-2396 ◽

Cited By ~ 2

Author(s):

S Airaksinen ◽

M Nikinmaa

Keyword(s):

Blood Cell ◽

Red Blood Cell ◽

Haemoglobin Concentration ◽

Oxygen Affinity ◽

Equilibrium Curve ◽

Volume Changes ◽

Oxygen Equilibrium ◽

The Mean ◽

The Right ◽

Oxygen Equilibrium Curve

We investigated whether the oxygen affinity of lamprey haemoglobin decreases with increasing oxygen concentration at the high (1025 mmol l-1 monomeric) haemoglobin concentrations prevailing within the erythrocytes. The intracellular concentration of haemoglobin was experimentally adjusted by shrinking the cells osmotically: the osmolality of the equilibration medium was increased from approximately 250 mosmol kg-1 by 90 mosmol kg-1 to 340 mosmol kg-1 or by 180 mosmol kg-1 to 430 mosmol kg-1 by adding sucrose in the medium. This increased the mean cellular haemoglobin concentration from 16.9±0.23 mmol l-1 (monomeric haemoglobin) to 20.0±0.20 mmol l-1 (monomeric haemoglobin) and to 23.0±0.36 mmol l-1 (monomeric haemoglobin), respectively (means ± s.e.m., N=3540; all the samples from 78 different pools of blood at each osmolality combined). The oxygen equilibrium curves at each osmolality were determined by Tucker's method. An increase in haemoglobin concentration shifted the oxygen equilibrium curve to the right as indicated by the P50 values, which were 4.26±0.07 kPa at the lowest, 4.64±0.13 kPa at the intermediate and 5.64±0.40 kPa (means ± s.e.m., N=78) at the highest haemoglobin concentrations. The decrease in haemoglobin oxygen-affinity was attributed to the volume changes, since the intracellular pH did not decrease with increasing mean cellular haemoglobin concentration. Thus, the variations in red blood cell volume commonly observed during hypoxia may play a role in the regulation of haemoglobin function.

Download Full-text

Hypoxia, Hormones, and Red Blood Cell Function in Chick Embryos

Physiology ◽

10.1152/nips.01426.2002 ◽

2003 ◽

Vol 18 (2) ◽

pp. 77-82 ◽

Cited By ~ 1

Author(s):

Stefanie Dragon ◽

Rosemarie Baumann

Keyword(s):

Blood Cell ◽

Red Blood Cell ◽

Adrenergic Receptor ◽

Cell Function ◽

Oxygen Affinity ◽

Terminal Differentiation ◽

Receptor Activation ◽

Avian Embryos ◽

Hypoxic Conditions ◽

Hemoglobin Oxygen Affinity

The red blood cell function of avian embryos is regulated by cAMP. Adenosine A2A and β-adrenergic receptor activation during hypoxic conditions cause changes in the hemoglobin oxygen affinity and CO2 transport. Furthermore, experimental evidence suggests a general involvement of cAMP in terminal differentiation of avian erythroblasts.

Download Full-text

The Effects of Hypersaline Exposure on Oxygen-Affinity of the Blood of the Freshwater Teleost Catostomus Commersoni

Journal of Experimental Biology ◽

10.1242/jeb.142.1.125 ◽

1989 ◽

Vol 142 (1) ◽

pp. 125-142 ◽

Cited By ~ 1

Author(s):

R. L. WALKER ◽

P. R. H. WILKES ◽

C. M. WOOD

Keyword(s):

Blood Cell ◽

Red Blood Cell ◽

Oxygen Affinity ◽

Plasma Osmolality ◽

Control Fish ◽

Nucleoside Triphosphate ◽

Strong Ion Difference ◽

Plasma Catecholamine ◽

Catostomus Commersoni

After 10 days' exposure to an environmental salinity of 300 mosmol kg−1 NaCl, the freshwater stenohaline teleost Catostomus commersoni exhibited an increase in plasma osmolality and a reduction in plasma strong ion difference (SID). There were reductions in plasma pH (pHe), red blood cell (RBC) pH (pHi), plasma total CO2 and erythrocyte nucleoside triphosphate (NTP) concentration, and increases in mean erythrocyte volume and plasma catecholamine levels. Despite the acidosis, the in vitro haemoglobin oxygen-affinity of blood from saline-acclimated fish was not significantly different from that of control fish (held in fresh water) which had higher pHe and pHi values at the PCO2 tensions used. In vitro adjustment of SID of blood from control fish to approximate that of the saline-acclimated fish by the addition of NaOH and HCl significantly reduced pHe, pHi and the haemoglobin oxygen-affinity. Adjustment of the plasma osmolality of blood from control fish to values identical to those of the saline-acclimated fish by the addition of NaCl in vitro did not alter the haemoglobin oxygen-affinity. An increase in catecholamine concentration and a decrease in red blood cell NTP concentration in the saline-acclimated fish may have been compensatory mechanisms to maintain haemoglobin oxygen-affinity against acidosis-induced Bohr and Root effects during saline exposure.

Download Full-text

Red cell 2,3-diphosphoglycerate and oxygen affinity of hemoglobin in patients with thyroid disorders

Blood ◽

10.1182/blood.v52.1.181.bloodjournal521181 ◽

1978 ◽

Vol 52 (1) ◽

pp. 181-185

Author(s):

CG Zaroulis ◽

IA Kourides ◽

CR Valeri

Keyword(s):

Blood Cell ◽

Oxygen Transport ◽

Red Blood Cell ◽

Clinical Status ◽

Oxygen Affinity ◽

Red Cell ◽

Transport Function ◽

Oxygen Affinity Of Hemoglobin ◽

2,3 Dpg

We measured red blood cell 2,3-diphosphoglycerate (2,3-DPG), adenosine triphosphate (ATP), and the P50 value in vitro of the oxyhemoglobin dissociation curve, which is the oxygen tension at half saturation of hemoglobin, in order to quantitate red blood cell oxygen transport function in individuals who were diagnosed as hypothyroid, euthyroid, or hyperthyroid based on measurements of thyroxine (T4), triiodothyronine (T3), thyrotropin (TSH), and their clinical status. Hypothyroid (mean T4 2.8 microgram/dl, T3 49 ng/dl, TSH 37 microU/ml) and hyperthyroid (mean T4 14 microgram/dl, T3 271 ng/dl, TSH less than 0.7 microU/ml) patients had normal red cell 2,3-DPG and ATP levels and normal P50 values in vitro. The known changes in oxygen consumption produced by alterations in thyroid hormone levels in patients with hypothyroidism or hyperthyroidism did not affect red blood cell oxygen transport function.

Download Full-text