Lactic Acid in Rest and Work at High Altitude

Edwards, H. T.

doi:10.1152/ajplegacy.1936.116.2.367

Cited by 106 publications

(38 citation statements)

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“…In fact, some authors (Bender et al, 1989;Brooks et al, 1992Brooks et al, , 1998 have demonstrated that the low blood lactate concentration primarily depends on a reduced net lactate release from muscle fibres. The decrease in lactate accumulation could also be explained by the reduced alkalic reserves at high altitude (Edwards, 1936;Cerretelli, 1967;West, 1986). Although Kayser et al (1993) did not observe an increase in the peak of blood lactate concentration after ingestion of bicarbonate, it must be considered that bicarbonate is effective in muscle pH regulation only when it really enters the muscle cell and, after its conversion to CO 2, leaves the cell in the form of dissolved CO2.…”

Section: Discussionmentioning

confidence: 99%

Effects of temperature and extracellular pH on metabolites: kinetics of anaerobic metabolism in resting muscle by 31P- and 1H-NMR spectroscopy

Vezzoli

Gussoni

Greco

et al. 2003

Journal of Experimental Biology

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Muscle metabolism is susceptible to a variety of stressing agents affecting particularly the overall rate of energy turnover. As is well known, temperature is a key environmental determinant of the activity of cellular multienzyme systems, such as muscle. In fact, this variable determines the kinetics and flux throughout biochemical pathways, particularly metabolic rates. Another key environmental determinant of cellular multienzyme system activity is intracellular pH. In general, owing to the presence of pH-sensitive ionizing groups, enzymes are active only over a limited range of pH with a definite optimum. Moreover, extracellular acidosis has been shown to play a key role in metabolic processes (Hood et al., 1988). Also, severe hypoxia and anoxia may modulate the ATP demand by the cell (Hochachka, 1986a,b). Skeletal muscle is known to be one of the most hypoxia-tolerant tissues and, in O2-limiting conditions, can survive by means of a metabolic depression, thereby saving substrates and reducing deleterious end-product formation.Ectothermic vertebrates, such as the frog, that normally experience rapid and large variations in body temperature (T) and consequent acid-base state changes, based on physicochemical adaptations (Boutilier, 2001), appear to tolerate such changes with minimal metabolic disturbances. The effects of temperature variations on acid-base balance regulation mechanisms have been well documented (Reeves, 1969). The 'in vivo' blood pH of most studied ectothermic species decreases as temperature increases with a slope close to -0.018·pH·units·°C -1 (Malan et al., 1976). It has been suggested that ∆pH/∆T changes of such an extent can keep the histidine groups of proteins at an almost constant dissociation state (alphastat hypothesis; Reeves, 1972 Environmental stress, such as low temperature, extracellular acidosis and anoxia, is known to play a key role in metabolic regulation. The aim of the present study was to gain insight into the combined temperature-pH regulation of metabolic rate in frog muscle, i.e. an anoxia-tolerant tissue. The rate of exergonic metabolic processes occurring in resting isolated muscles was determined at 15°C and 25°C as well as at extracellular pH values higher (7.9), similar (7.3) and lower (7.0) than the physiological intracellular pH. 31 P and 1 H nuclear magnetic resonance spectroscopy high-resolution measurements were carried out at 4.7·T in isolated frog (Rana esculenta) gastrocnemius muscle during anoxia to assess, by means of reference compounds, the concentration of all phosphate metabolites and lactate. Intra-and extracellular pH was also determined.In the range of examined temperatures (15-25°C), the temperature dependence of anaerobic glycolysis was found to be higher than that of PCr depletion (Q 10 =2.3). High-energy phosphate metabolism was confirmed to be the initial and preferential energy source. The rate of phosphocreatine hydrolysis did not appear to be affected by extracellular pH changes. By contrast, independent of the intracellular pH value, at ...

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Section: Discussionmentioning

confidence: 99%

Effects of temperature and extracellular pH on metabolites: kinetics of anaerobic metabolism in resting muscle by 31P- and 1H-NMR spectroscopy

Vezzoli

Gussoni

Greco

et al. 2003

Journal of Experimental Biology

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“…Not to be inattentive or otherwise neglectful of then contemporary science, as described by Reeves [ 9 ], pioneer workers such as Dill et al [ 10 ] and Edwards et al [ 11 ] took an early interest in the lactate response at altitude. In the 1929 expeditions to Leadville, CO [ 10 ] and the Andes in Chile [ 11 ] observed in unacclimatized sojourners that during rest and exercise, blood lactate concentrations were evaluated at altitude above those seen at sea level.…”

Section: Early Studies At Altitudementioning

confidence: 99%

“…In the 1929 expeditions to Leadville, CO [ 10 ] and the Andes in Chile [ 11 ] observed in unacclimatized sojourners that during rest and exercise, blood lactate concentrations were evaluated at altitude above those seen at sea level. The conclusion at that time regarding the elevation in blood lactate was classic and based on the Pasteur Effect , glycolytic fl ux was increased because oxidative metabolism was limited.…”

Section: Early Studies At Altitudementioning

confidence: 99%

Energy Flux, Lactate Shuttling, Mitochondrial Dynamics, and Hypoxia

Brooks

2016

Advances in Experimental Medicine and Biology

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Our understanding of what happens in working muscle and at the whole-body level at sea level and at high altitude is different from that a few years ago. If dietary CHO and nutrition are adequate, at sea level metabolism shifts from a mix of lipid and CHO-derived fuels toward carbohydrate (glycogen, glucose, and lactate) oxidation at moderate and greater exercise intensities. As given by the Crossover Concept, a percentage to total energy expenditure, lipid oxidation is greatest at exercise power outputs eliciting 45-50 % of VO2max with greater intensities requiring relatively more CHO and lesser lipid oxidation. At altitude, a given exercise power output is achieved at a greater relative intensity expressed as % VO2max. Hence, exercise under conditions of hypoxia requires greater glycolytic flux, and lactate production than does the same effort at sea level, normoxic conditions. Glycolytic flux is further augmented at altitude by the effect of hypoxemia on sympathetic nervous system activity. Hence, augmented lactate production during exercise is adaptive. Over the short term, accelerated lactate flux provides ATP supporting muscle contraction and balances cytosolic redox. As well, lactate provides and energy substrate and gluconeogenic precursor. Over a longer term, via redox and ROS-generating mechanisms, lactate may affect adaptations in mitochondrial biogenesis and solute (glucose and lactate) transport. While important, the energy substrate, gluconeogenic, and signaling qualities of lactate production and disposal at altitude need to be considered within the context of overall dietary energy intake and expenditure during exercise at sea level and high altitude.

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“…I hope always to be faithful in prayer and trust our Lord, Amen." Subsequent Observations.-The patient was discharged from the hospital on Sept. 16,1936. She looked around Boston for a job and then went home.…”

Section: Report Of Casementioning

confidence: 99%

“…At high altitude diminished concentration of bicarbonate is not associated with increased concentration of lactate. 16 In experi¬ ments on hyperventilation at sea level, however, the increase in concen¬ tration of lactate may be 2 or 3 milliequivalents per liter.17 This may account for the greater portion of the undetermined acid.…”

Section: Commentmentioning

confidence: 99%

Acid-Base Balance of the Blood in a Patient With Hysterical Hyperventilation

Talbott¹

1938

Arch NeurPsych

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Lactic Acid in Rest and Work at High Altitude

Cited by 106 publications

References 0 publications

Effects of temperature and extracellular pH on metabolites: kinetics of anaerobic metabolism in resting muscle by 31P- and 1H-NMR spectroscopy

Effects of temperature and extracellular pH on metabolites: kinetics of anaerobic metabolism in resting muscle by 31P- and 1H-NMR spectroscopy

Energy Flux, Lactate Shuttling, Mitochondrial Dynamics, and Hypoxia

Acid-Base Balance of the Blood in a Patient With Hysterical Hyperventilation

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