Blood ammonia and ventilation at maximal exercise

This study, intended to evaluate the role of ammonia (NH3) as a ventilatory stimulus, was conducted in three groups of subjects: 14 sedentary individu als, 12 triathletes, 5 patients with a glycolytic deficiency (Mc Ardle dise ase). All subjects performed maximal exercise tests on a cycle ergometer. V entilation measured at maximal oxygen consumption (V-E 100%) was correlated with lactatemia(lactate 100%) and ammonemia(NH3 100%) in the sedentary gro up, but only with ammonemia in triathletes, although NH3 100% and lactate 1 00% were correlated in both groups, which suggests that correlation between VE 100% and NH3 100% is not a false correlation. In patients with Me Ardle disease, unable to produce lactate during exercise, VE 100% was correlated with NH3 100%. NH3 may act indirectly by increasing the production of lact ate in cerebral tissue. Another hypothesis rests on the fact chat the catab olism of ammonia leads to an increase in intracerebral glutamate which may act as a ventilatory stimulus.