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Regulation of arterial H + during exercise in man
Author(s) -
Wasserman Karlman,
Sun XingGuo,
Stringer William W.,
Beaver William L
Publication year - 2010
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.24.1_supplement.615.6
Subject(s) - acidosis , lactic acidosis , work rate , metabolic acidosis , medicine , chemistry , respiration , respiratory acidosis , endocrinology , cardiology , heart rate , anatomy , blood pressure
Despite a relatively high H + production compared to total body H + , arterial H + concentration ([H + ]a) is well regulated during exercise. This is achieved by ΔVE of exercise. The study objective was to quantify [H + ]a regulation below and above the lactic acidosis threshold (LAT) during exercise. Methods Two progressively increasing cycle exercise protocols were performed. Results In the first, we related VE to [H + ]a and PaCO2. All subjects developed an acidosis with exercise, respiratory below and metabolic above LAT. ΔVE correlated with Δ[H + ]a up to the LAT, (ΔVE/Δ[H + ]a ¡Ö15L/nM). The increase in [H + ]a (2–3 nM) was attributable to PaCO2 increase. ΔVE correlated with ΔPaCO2 only up to the LAT. Above LAT, VE increased less with increasing [H + ]a. The 2nd protocol compared a 4‐fold difference in work rate increase to determine the effect of time on the VE response. Below LAT, VE tracked VCO2 with equal sensitivity for the two rates. Above the LAT, VE was steeper for the more slowly increasing work rate. Conclusion [H + ]a is regulated by sensitive ventilatory control mechanisms. ΔVE/Δ[H + ]a below the LAT is of CO2 origin, rapid and steep, not‐detectibly affected by time. In contrast, ΔVE/Δ[H + ]a above LAT is less and steeper with time. The difference between the ΔVE responses to the 2 H + species is likely due to differences in chemoreceptor permeability of lipophilic and lipophobic forms of H + .