Abstract des Autors

Red cell concentrations of hemoglobin (MCHC), H+, Na+, K+, Mg++, Cl- were measured in femoral venous blood of six untrained (UT), six endurance trained (TR) and three semitrained (ST) subjects during graded increasing work (4,8,12,18 and 24 mkp/s, 10-15 min on each step) on a bicycle ergometer. Before exercise no significant differences were detected for the measured variables when comparing UT and TR. During exercise MCHC, (Na+), (K+) and (Mg++) remained constant indicating lack of water shift into the erythrocytes in spite of a marked acidosis (lowest pH Blood value 7.225). This lack resulted from an elevated extracellular osmolality. (H+) Ery and (Cl-) Ery maximally increased by 2.0x 10-8 eg/kg H2O and 10 meg/l, respectively, The change was markedly greater in UT than in TR at equal load. However, if (H+) Ery and (Cl-) Ery were related to pH of whole blood, differences between groups almost disappeared and the ions were distributed as predictable from in vito experiments (Fitzsimmons and Sendroy, 1961). Behaviour of H+ and Cl- may be of importance for oxygen dissociation under in vivo conditions.