Blood Volume, Hemoglobin Mass, and Peak Oxygen Uptake in Older Adults: The Generation 100 Study

Purpose: To investigate the association between blood volume, hemoglobin mass (Hbmass), and peak oxygen uptake (VO2peak) in healthy older adults.Methods: Fifty fit or unfit participants from the prospective randomized Generation 100 Study (n = 1,566) were included (age- and sex-specific VO2peak above or below average values). Blood, plasma, and erythrocyte volume and Hbmass were tested using the carbon monoxide rebreathing method within 1 week after VO2peak testing.Results: Mean age, BMI, Hbmass, blood volume, and VO2peak were 73.0 ± 2.1 years, 24.8 ± 3.3 kg·m2, 10.0 ± 1.7 g·kg−1, 76.4 ± 11.8 mL·kg−1, and 33.5 ± 8.4 mL·kg−1·min−1. VO2peak in fit and unfit participants and women and men were 38.6 ± 6.5 and 25.8 ± 3.8 mL·kg−1·min−1, 30.7 ± 7.6 mL·kg−1·min−1, and 35.5 ± 8.5 mL·kg−1·min−1, respectively. Women were shorter (Δ14 cm), leaner (Δ13 kg), and with less muscle mass (Δ9%) than men (P < 0.05). Relative erythrocyte volume and Hbmass were lower in women, and blood and erythrocyte volume and Hbmass were higher in the fit participants (P < 0.05). Hbmass and erythrocyte volume explained 40 and 37%, respectively, of the variability in VO2peak, with a limited effect of physical-activity adjustment (40 and 38%, respectively). Blood and plasma volume explained 15 and 25%, respectively, of VO2peak variability, and the association was strengthened adjusting for physical activity (25 and 31%, respectively), indicating a training-dependent adaptation in plasma but not erythrocyte volume (p ≤ 0.006).Conclusions: Blood and plasma volumes were moderately associated with VO2peak in healthy older men and women, and the association was strengthened after adjustment for physical activity. Hbmass and erythrocyte volume were strongly associated with VO2peak but unrelated to physical activity.

TRANSMEMBRANE ION AND WATER TRANSPORTS IN ERYTHROCYTE VOLUME HOMEOSTASIS: AN OVERVIEW OF THE PHYSIOLOGIC PROCESSES

Background: The intraerythrocytic concentrations of ions (Na+, K+, Cl- and HCO3-) play key roles in maintaining erythrocyte volume homeostasis. Anisosmotic and isosomotic changes of these ion concentrations challenge erythrocyte volume to either shrink or swell, thereby sending signals to activate regulatory volume mechanisms that are mediated by ion transporters. Ion fluxes directed inwardly or outwardly with obliged water movements do restore the erythrocyte volume to its steady state. These physiological phenomena prevent the erythrocyte from becoming overhydrated or dehydrated with the consequence of intravascular haemolysis or senescent changes associated with eryptosis. Objectives: To review the literature on the physiological processes associated with transmembrane ion and water transports during erythrocyte volume homeostasis. Method: Offline and online libraries were searched with indexing tools using keywords derived from the subject area of review. Conclusions: The review has highlighted the physiological concepts involved in erythrocyte volume homeostasis in relation to the engaged transmembrane ion and water transport systems, which can influence experimental designs to study ion and water channel blockers and channelopathies of erythrocytes.

Causal-Investigative Analysis of the Formation of Anemia in Children

The purpose of the study was to determine the main causal factors in the formation of anemia in children of Ukraine, depending on the morphometric changes in erythrocytes of blood, indicators of iron metabolism for the formation of a risk group for oncohematological diseases. Material and methods. 770 children were examined: 724 with anemia, 46 with acute lymphoblastic leukemia. We studied the parameters of the erythrocyte lineage of hematopoiesis, morphometric parameters of erythrocytes, indicators of iron metabolism (serum iron, ferritin, transferrin, the transferrin saturation with iron, hematocrit, the content of δ-aminolevulinic acid and coproporphyrin in urine, pituitary thyroid stimulating hormone depending on the type of somatic pathology. Anemic states were distributed taking into account the average erythrocyte volume and the average hemoglobin content in the erythrocyte, and dividing diagnoses microcytic-hypochromic or normocytic-normochromic anemia, respectively. Results and discussion. The study showed that in children with normocytic-normochromic anemia, the number of erythrocytes and hematocrit were lower than in patients with microcytic-hypochromic anemia, while average erythrocyte volume, average hemoglobin content, serum iron, serum ferritin and transferrin saturation with iron were higher. The number of reticulocytes in the peripheral blood in all the examined subjects was standard. That is, the anemic conditions in children differed in ferrokinetic parameters, in particular, with and without iron deficiency. Taking into account the age of the children and the reasons for the development of anemia, a third of the girls of puberty with microcytic-hypochromic anemia had menorrhagias. In children under 6 years of age with normocytic-normochromic anemia, diseases of the gastrointestinal tract were more often registered; in the older 6 years – gastrointestinal diseases, helminthiasis and allergic reactions compared with patients with microcytic-hypochromic anemia. The development of normocytic-normochromic anemia in children and the functioning of the gastrointestinal tract were influenced by drug treatment for chronic pathology in the body. All children with anemia had an irrational diet. Porphyria was diagnosed in 3.8% of children with microcytic-hypochromic anemia. In 12.7% of children with normocytic-normochromic anemia, the serum thyroid stimulating hormone level was at the upper limit of the reference value (mean 3.3±0.6) mU/L), which correlated with a reduced number of erythrocytes in blood (r = -0.65) and increased values of average erythrocyte volume (r = 0.41) and average hemoglobin content (r = 0.35), and indicates changes in the erythrocyte lineage of hematopoiesis associated with the initial manifestations of thyroid hypofunction. An excess of iron was observed in 7.1% of older boys with normocytic-normochromic anemia, which requires additional examination. In patients with acute lymphoblastic leukemia were diagnosed with normocytic-normochromic anemia of varying severity. The serum ferritin level was (272.1±28.4) ng/ml and was significantly higher than in children with normocytic-normochromic anemia. In 12 of 46 patients, transferrin saturation with iron was increased and amounted to (70.2±2.3)%. Moreover, the higher the level of serum iron and serum ferritin, the higher was the transferrin saturation with iron (rs = 0.5; rs = 0.85). An inverse correlation was established between transferrin saturation with iron, patient survival (rs = -0.45) and a higher probability of death (rs = -0.46). Conclusion. Children with normocytic-normochromic anemia require in-depth examination and constitute a risk group for the development of myelodysplastic syndrome and leukemia

Mutations in the Gardos channel (KCNN4) are associated with hereditary xerocytosis

Key Points Mutations in the Gardos channel, encoded by the KCNN4 gene, were identified in individuals from 2 hereditary xerocytosis kindreds. These findings support recent data indicating the Gardos channel plays a role in normal erythrocyte volume homeostasis.