Browsing by Autor "Schmidt, W"

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    Effects of chronic hypoxia and exercise on plasma erythropoietin in high-altitude residents
    (Facultad de Medicina, Enfermería, Nutrición y Tecnología Médica, 1993) Schmidt, W
    Abstract The present study was performed to evaluate the effects of chronic inspiratory hypoxia and its combination with physical exercise on plasma erythropoietin concentration ([EPO]). Eight natives from the Bolivian Plateau were investigated at 3,600 m above sea level at rest as well as during and up to 48 h after exhaustive exercise (EE) and 60 min of submaximal (60%) cycle ergometer exercise (SE). Ten sea-level subjects were used as a control group for resting values. The mean resting plasma [EPO] of the high-altitude group (19.5 +/- 0.7 mU/ml) did not differ from that of the sea-level group (18.1 +/- 0.4 mU/ml) but was higher than would be expected from the relationship between [EPO] and hematocrit at sea level. Five hours after both types of exercise, [EPO] decreased by 2.1 +/- 0.8 (EE, P < 0.01) and 1.6 +/- 0.8 mU/ml (SE, P < 0.05); 48 h after SE, [EPO] increased by 2.6 +/- 0.9 mU/ml (P < 0.05). It is concluded that 1) high-altitude natives need relatively high [EPO] to maintain their high hematocrit and 2) exercise at low basal arterial PO₂ does not directly increase plasma [EPO] in high-altitude residents but seems to exert suppressive effects.
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    Effects of exercise on plasma erythropoietin in natives living permanently at high altitude
    (Facultad de Medicina, Enfermería, Nutrición y Tecnología Médica, 1992) Schmidt, W
    Abstract. The effects of inspiratory hypoxia on the erythropoietin (EPO) system decisively depend on the duration of the exposure to the hypoxic environment. Whereas a stay of some hours in a hypobaric chamber leads to markedly increased serum [EPO] (Eckardt et al. 1989), it could be demonstrated by Milledge and Cotes (1985) that members of a Himalaya expedition had, after a rapid increase in EPO values, presented decreasing EPO values during the second half of their altitude exposure. Furthermore, Winslow et al. (1989) showed low EPO concentrations in the blood of high-altitude natives from Nepal and Chile, which are similar to those of subjects living at sea level. The reasons for the adaptation of the EPO response to chronic hypoxia are not completely understood. It may only in part be attributed to other adaptive processes, e.g., increased hemoglobin concentration [Hb] or lower pH values.