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Summary

Alterations in acid-base-balance are accompanied by changes in blood osmolality. In vitro, in oxygenated blood the following relationship was found: Δosm = -31.7 × ΔpH. During physical activity (cycle-ergometer, workload beginning with 50 watt, increasing in steps of 50 watt every 3 min; n = 10) the in vivo relationship is Δosm = -136.6 × ΔpH + 1.9. A pH decrease of 0.2 units results in an increase in osmolality of 29.2 mosmol/kg H2O. Only 6.3 mosmol are due to acid-base-balance changes because the rise in lactic acid concentration is compensated for by the elimination of bicarbonate. The remaining increase of 22.7 mosmol/kg H2O is caused to a large extent by a water shift into the working muscles due to osmotic effects related to the anaerobic metabolism (ΔOsm = 2.05 × Δ[Lac] + 2.7). More than 50% of the exercise hemoconcentration can be explained by these osmotic effects. The same mechanism seems to play an important role during the early stage of hemorrhagic shock.

Exercise-Induced Hemoconcentration and Osmolality

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Copyright information

© Springer-Verlag Berlin Heidelberg 1984

Authors and Affiliations

  • N. Maassen
  • D. Böning

There are no affiliations available

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