In:
Journal of Applied Physiology, American Physiological Society, Vol. 102, No. 5 ( 2007-05), p. 1936-1944
Abstract:
We examine the influence of the cytosolic and membrane-bound contents of carbonic anhydrase (CA; CAII, CAIII, CAIV, and CAXIV) and the muscle content of proteins involved in lactate and proton transport [monocarboxylate transporter (MCT) 1, MCT4, and Na + /H + exchanger 1 (NHE1)] on work capacity during supramaximal exercise. Eight healthy, sedentary subjects performed exercises at 120% of the work rate corresponding to maximal oxygen uptake (Ẇ max ) until exhaustion in placebo (Con) and metabolic alkalosis (Alk) conditions. The total (W tot ) and supramaximal work performed (W sup ) was measured. Muscle biopsies were obtained before and immediately after standardized exercises (se) at 120% Ẇ max in both conditions to determine the content of the targeted proteins, the decrease in muscle pH (ΔpH m ), and the muscle lactate accumulation ([Lac] m ) per joule of W sup (ΔpH m /W sup-se and Δ[Lac] m /W sup-se , respectively) and the dynamic buffer capacity. In Con, W sup was negatively correlated with ΔpH m /W sup-se , positively correlated with Δ[Lac] m /W sup-se and MCT1, and tended to be positively correlated with MCT4 and NHE1. CAII + CAIII were correlated positively with ΔpH m /W sup-se and negatively with Δ[Lac] m /W sup-se , while CAIV was positively related to W tot . The changes in W sup with Alk were correlated positively with those in dynamic buffer capacity and negatively with W sup in Con. Performance improvement with Alk was greater in subjects having a low content of proteins involved in pH regulation and lactate/proton transport. These results show the importance of pH regulating mechanisms and lactate/proton transport on work capacity and the role of the CA to delay decrease in pH m and accumulation in [Lac] m during supramaximal exercise in humans.
Type of Medium:
Online Resource
ISSN:
8750-7587
,
1522-1601
DOI:
10.1152/japplphysiol.00691.2006
Language:
English
Publisher:
American Physiological Society
Publication Date:
2007
detail.hit.zdb_id:
1404365-8
SSG:
12
SSG:
31
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