Abstract des Autors

During and after two successive incremental cycle ergometer tests (tests A and B), plasma potassium concentration (<K+>p), plasma pH (pHp), plasma partial pressure of carbon dioxide, blood lactate concentration (<Lac>b) and ventilation (VE) were measured. While there was a good correlation between the increase in <K+>p and VE or pHp, respectively, in test A, in test B a close correlation was found only between the increase in VE and <K+>p (r > 0.9 for nearly all single cases; r was 0.84 and 0.89 for all (pooled) cases in tests A and B, respectively; the correlation coefficients between changes in pHp and VE in tests A and B were r = 0.74 and r = 0.28, respectively, and r = 0.89 and r = 0.10 between the changes in <Lac>b and VE in tests A and B). The close relationship for individuals between VE and <K+>p in tests A and B supported the hypothesis that the extracellular increase in <K+> may contribute to the ventilatory drive during exercise. The comparison of the results of tests A and B further indicated that the relationship between pHp and VE was dependent on the experimental design, and that pHp and VE changes are unlikely to be cause and effect.