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  • 1
    Electronic Resource
    Electronic Resource
    Lactate/H+ uptake by red blood cells during exercise alters their physical properties (1996)
    Springer
    European journal of applied physiology 75 (1996), S. 54-61 
    Details
    ISSN: 1439-6327
    Keywords: Key words Density ; Exertion ; Haemolysis ; Lactic acid ; Osmosis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract  We investigated whether uptake of lactate anions by red blood cells (RBC) during maximal exercise altered certain cellular physical properties including volume, density and osmotic fragility. Irrespective of whether individuals undertook 1 min of exercise at maximal effort or a progressive exercise test to exhaustion, whole-blood lactate concentration increased about tenfold relative to pre-exercise values (P〈0.001). The plasma and cellular concentrations of lactate increased uniformly, which maintained a constant plasma-to-cell gradient. Exercise-induced increases in RBC osmotic fragility (P〈0.001) and mean cell volume (MCV;P〈0.05), and decreases in mean cell haemoglobin concentration (MCHC;P〈0.05) and cell density (P〈0.005) also occurred. These exercise-induced cellular responses could be simulated in vitro by treating blood with L-lactic acid (15 mm), but not by low pH (7.1) or L-lactate alone. The uptake of lactate by RBCs during vigorous exercise alters certain cellular properties. Although the physiological implications of these changes are unclear, the traditional view that the lactate anion has no known harmful effects should be reconsidered.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s004210050126
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  • 2
    Electronic Resource
    Electronic Resource
    Changes in the susceptibility of red blood cells to oxidative and osmotic stress following submaximal exercise (1995)
    Springer
    European journal of applied physiology 70 (1995), S. 427-436 
    Details
    ISSN: 1439-6327
    Keywords: Antioxidant ; Erythrocytes ; Free radicals ; Exertion ; Haematology
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Red blood cell (RBC) susceptibility to oxidative and osmotic stress in vitro was investigated in cells from trained and untrained men before and after submaximal exercise. Whilst no significant change in peroxidative haemolysis occurred immediately after 1 h of cycling at 60% of maximal aerobic capacity ( $$\dot V{\text{O}}_{\text{2}} $$ max), a 20% increase was found 6 h later in both groups (P〈0.05). The RBC osmotic fragility decreased by 15% immediately after exercise (P〈0.001) and this was maintained for 6 h (Ps〈0.001). There was an associated decrease in mean cell volume (P〈0.05). Training decreased RBC susceptibility to peroxidative haemolysis (P〈0.025) but it did not influence any other parameter. These exercise-induced changes were smaller in magnitude but qualitatively similar to those found in haemopathological states involving haem-iron incorporation into membrane lipids and the short-circuiting of antioxidant protection. To explore this similarity, a more strenuous and mechanically stressful exercise test was used. Running at 75% $$\dot V{\text{O}}_{\text{2}} $$ max for 45 min reduced the induction time of O2 uptake (peroxidation), consistent with reduced antioxidation capacity, and increased the maximal rate of O2 uptake in RBC challenged with cumene hydroperoxide (P〈0.001). The proportion of high-density RBC increased by 10% immediately after running (P〈0.001) but no change in membrane-incorporated haem-iron occurred. In contrast, treatment of RBC with oxidants (20–50 μmol·l−1 in vitro increased cell density and membrane incorporation of haem-iron substantially. These results showed that single episodes of submaximal exercise caused significant changes in RBC susceptibility to oxidative and osmotic stress. Such responses may account for the increase in RBC turnover found in athletes undertaking strenuous endurance training.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00618494
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  • 3
    Electronic Resource
    Electronic Resource
    Rapid alterations in cellular morphology and plasma membrane structure induced in rat thymocytes by mitogenic stimuli (1979)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Cellular Physiology 101 (1979), S. 523-528 
    Details
    ISSN: 0021-9541
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Under conditions where a maximum stimulation of 3-O-methyl-glucose transport is observed, three thymocyte mitogens (concanavalin A, ionophore A23187 and hydrogen peroxide) cause cell rounding and a decrease in the density of intra-membrane particles on the plasma membrane. The early effects of mitogens on the thymocyte plasma membrane are similar to those of osmotic shock.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jcp.1041010318
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  • 4
    Electronic Resource
    Electronic Resource
    On the stimulation of rat thymocyte 3-0-methyl-glucose transport by mitogenic stimuli (1978)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Cellular Physiology 96 (1978), S. 303-308 
    Details
    ISSN: 0021-9541
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Pretreatment of rat thymus lymphocytes with N-ethyl-maleimide prevents the stimulation of 3-0-methyl-glucose transport by concanavalin A or ionophore A23187 but does not affect the ability of concanavalin A to induce a rapid increase in cellular Ca2+ uptake. N-ethyl-maleimide added after concanavalin A amplifies rather than prevents the subsequent stimulation of 3-0-methyl-glucose transport. Incubation of thymocytes with concanavalin A produces a decrease of 43% in the apparent Ki for phloretin, a competitive inhibitor of 3-0-methyl-glucose transport, without affecting the apparent Km for the substrate. Similarly, very low concentrations of cytochalasin B inhibit concanavalin A-stimulated glucose transport preferentially, without markedly affecting the unstimulated transport rates. The similarity between concanavalin A-stimulated 3-0-methyl-glucose transport in thymocytes and insulin-stimulated glucose transport in adipose tissue, with particular emphasis on the effects of the modifying agents described in this paper, is discussed.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jcp.1040960305
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    Paper (German National Licenses)
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