Ammonium ion and the anaerobic threshold in man.
To determine if ammonium ion plays a role in the lactate and ventilatory thresholds of incremental exercise, we investigated the effects on blood lactate and ventilation of NH(4+)-buffering by monosodium glutamate. Six normal volunteers underwent intravenous loading with MSG, 9 g, in a randomized, double-blind, saline placebo controlled crossover study. Four of the six subjects had a greater than 10 percent fall in peak (NH4+) following MSG (37 +/- 2.0 vs 25 +/- 4.3 micrograms/dl p = 0.003, PLB vs MSG). When MSG blunted the rise in venous (NH4+) during exercise, uncoupling of the LT and VT was observed. Specifically, with suppression of peak exercise (NH4+) by MSG, the LT was delayed (r = -0.84, p = 0.03), the VT was earlier (r = 0.86, p = 0.02), and the VO2 difference between the LT and VT widened (r = -0.90, p = 0.02). We conclude that NH4+ plays a role in determining the LT and VT of incremental exercise and that the VT may not be exclusively dependent on blood lactate.
Systrom
D M
DM
Pulmonary and Critical Care Unit (Medical Services), Massachusetts General Hospital, Harvard Medical School, Boston 02114.
Fragoso
C V
CV
Kanarek
D J
DJ
Kazemi
H
H
D000641:Ammonia / Q000097:blood*; D015308:Anaerobic Threshold / Q000502:physiology*; D004311:Double-Blind Method; D015444:Exercise / Q000502:physiology; D006801:Humans; D007773:Lactates / Q000097:blood; D019344:Lactic Acid; D012970:Sodium Glutamate
D007773:Lactates; D019344:Lactic Acid; D000641:Ammonia; D012970:Sodium Glutamate