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1 Laboratoire de Physiologie et de Biomécanique de l'Exercice Musculaire, UFRAPS Rennes 2, UPRES A 1274, Campus la Harpe, CS 24414, 35044 Rennes Cedex; and 2 Laboratoire de Biologie Cellulaire et Végétale, Faculté de Pharmacie, Université de Rennes 1, 35043 Rennes Cedex, France
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ABSTRACT |
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 TOP
 ABSTRACT
 INTRODUCTION
MATERIALS AND METHODS
RESULTS
DISCUSSION
REFERENCES
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Divergent literature data are found concerning the
effect of lactate on free radical production during exercise. To
clarify this point, we tested the pro- or antioxidant effect of lactate ion in vitro at different concentrations using three methods: 1) electron paramagnetic resonance (EPR) was used to study
the scavenging ability of lactate toward the superoxide aion
(O2
·) and hydroxyl radical (·OH); 2)
linoleic acid micelles were employed to investigate the lipid radical
scavenging capacity of lactate; and 3) primary rat
hepatocyte culture was used to study the inhibition of membrane lipid
peroxidation by lactate. EPR experiments exhibited scavenging
activities of lactate toward both O2· and ·OH;
lactate was also able to inhibit lipid peroxidation of hepatocyte
culture. Both effects of lactate were concentration dependent. However,
no inhibition of lipid peroxidation by lactate was observed in the
micelle model. These results suggested that lactate ion may prevent
lipid peroxidation by scavenging free radicals such as
O2· and ·OH but not lipid radicals. Thus lactate
ion might be considered as a potential antioxidant agent.
electron paramagnetic resonance experiments; linoleic acid autoxidation; lactate; lipid peroxidation; oxidative stress
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INTRODUCTION |
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TOP
ABSTRACT
INTRODUCTION
MATERIALS AND METHODS
RESULTS
DISCUSSION
REFERENCES
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MANY EXPERIMENTS
PERFORMED either in animals (1, 12) or
in humans (15, 19) have demonstrated that
physical exercise increases the production of reactive oxygen species
(ROS), thereby inducing oxidative stress. All these studies have
indicated that oxidative stress particularly appears during vigorous
and exhaustive exercise, in which lactate production is nonnegligible.
A question thus arises: to what extent is lactate itself responsible
for free radical production during exercise? The data on this subject are conflicting. In vitro studies performed on kidney slices and homogenates have reported an oxidant effect of lactic acidosis (28, 30). In in vivo experiments, Lovlin et
al. (23) observed a significant relationship between
plasma lactate concentration and lipid peroxidation, as evaluated by
malondialdehyde (MDA), during a progressive incremental exercise.
However, Anbar and Neta (2), in tests of the scavenging
activity of various and numerous agents toward the hydroxyl radical
(·OH), noted that the lactate ion acted as a moderate ·OH scavenger
at pH 9. Given the substantial increase of lactate metabolism during
exercise, it seems of fundamental importance to determine the exact
effect of the lactate ion alone on free radical production during
exercise. In vivo, lactate production during exercise can never be
dissociated from the concomitant acidosis, which is well known to be a
potent oxidative condition (28, 30). For this
reason, we investigated the effect of the lactate ion in vitro at
concentrations usually found at rest or during exercise. Lactate
concentrations ranged up to 60 mM because such high lactate levels can
be found in muscle (22, 29). Different
methods were employed to test the lactate effect on free radicals. Two
methods were used to determine its scavenging activity toward
superoxide anion (O2·), ·OH, and lipid radical.
We also investigated its cellular antilipoperoxidant effect by using
hepatocyte cultures. Lactate was dissolved in either aqueous or plasma
solution or culture medium at different concentrations.
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MATERIALS AND METHODS |
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TOP
ABSTRACT
INTRODUCTION
MATERIALS AND METHODS
RESULTS
DISCUSSION
REFERENCES
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Three methods were used to evaluate the scavenging activity of lactate ion toward free radicals. Lactate ion was dissolved in aqueous or plasma solution or culture at concentrations ranging from 1 to 60 mM, i.e., approximately the concentrations usually found in plasma either at rest (1 mM) or during exercise (10 and 15 mM) and in muscle during exercise (30 and 60 mM) (22).
Experimental Procedure
First method: Electron paramagnetic resonance study of the
scavenging activity of lactate toward ·OH and
O2·.
The electron paramagnetic resonance (EPR) method allows direct
determination of the specific scavenging activity of lactate for one
radical species.
· was produced by a xanthine-xanthine oxidase
system. Xanthine oxidase (Sigma Chemical) catalyzes the oxidation of
xanthine (Sigma Chemical) in the presence of molecular oxygen to yield uric acid and O2· as reaction products
(18). In the presence of the spin-trap DMPO, the
O2· leads to the production of DMPO-·OOH adduct, which can then be analyzed by EPR spectroscopy (9). More
precisely, 30 µl of xanthine oxidase (0.8 U/ml of water) was added to
a reaction mixture containing 100 µl ethanol (1 M), 30 µl xanthine
aqueous solution (10 mM), 20 µl DMPO (800 mM), and 20 µl of lactate
dissolved in water or plasma at different initial concentrations (10, 100, 150, 300, and 600 mM). Thus final lactate concentrations were 1, 10, 15, 30, and 60 mM. The EPR analysis was performed 2 min after the
addition of xanthine oxidase. As before, controls without lactate
contained water or plasma alone. The effect of lactate was estimated by
the percentage of variation in the DMPO-·OOH adduct compared with
that of the controls without lactate (representing 100%). In the
xanthine-xanthine oxidase system, lactate cannot react with preformed
DMPO-·OOH adduct. Thus postaddition experiments were not necessary.
However, the possible inhibition of xanthine oxidase by lactate was
tested by measuring the concentration of uric acid produced with and
without lactate. Lactate did not modify uric acid production by
xanthine oxidase. Thus lactate did not inhibit xanthine oxidase.
Second method: Effect of lactate ion on linoleic acid micelle
autoxidation.
Fatty acid micelles are a good model to study membrane lipid
peroxidation. It is well known that propagation of lipid peroxidation involves the peroxyl radical, a lipid radical (24). Thus,
by scavenging this radical, lactate will reduce lipid peroxidation. Linoleic acid (9,12-octadecadienoic acid) was purchased (Koch Light;
>99% pure). This fatty acid was dispersed with 0.5% Tween 20 (Merck)
in 0.01 M phosphate-buffered aqueous solution (pH = 9) under
nitrogen atmosphere. Linoleic acid concentration was 102
M, and this stock solution was stored at +4°C. Lactate was dissolved in phosphate buffer (pH = 7.4; 5 mM) at initial concentrations of
10, 100, 150, 300, and 600 mM, respectively, and stored at +4°C.
Aliquots of each stock solution were adjusted to pH 7.4 and mixed at
time zero to achieve a final linoleic acid concentration of 2.5 × 103 M and various final lactate concentrations of 1, 10, 15, 30, and 60 mM, respectively. Samples were placed in glass tubes and left in the dark under air at 37°C. Controls without lactate were placed in the same conditions. Linoleic acid autoxidation was determined by conjugated diene measurement. Measures were performed every 3 h except during the night by use of a Secomam S1000PC spectrophotometer with a UV lamp set at 234 nm.
Third method: Effect of lactate on oxidative stress induced in rat hepatocytes in culture. The cellular effect of lactate was tested by using primary rat hepatocyte cultures as model. An oxidative stress was induced in these cells by iron supplementation and was estimated by the extent of lipid peroxidation.
The reagents 1,1,3,3-tetramethoxypropane and sodium lactate were obtained from Sigma Chemical. A ferric nitrilotriacetate solution (Fe-NTA) was prepared according to the method of White and Jacobs (31). Briefly, 47 mg of nitrilotriacetic acid disodium salt (Sigma Chemical) and 20 mg of ferric ammonium citrate (Merck) were dissolved in 10 ml of sterile water to achieve a 10 mM solution of ferric iron.Cell Isolation and Culture
Hepatocyte cultures were prepared according to the protocol of Guguen et al. (20). For experimental purposes, some cultures were maintained for 4 h with Fe-NTA at a final iron concentration of 100 µM (25), and other cultures were supplemented for 4 h with Fe-NTA (100 µM) and lactate (1, 10, 15, 30, or 60 mM at final concentrations) dissolved in culture medium. Lipid peroxidation was estimated by the measure of free MDA released in culture medium using the HPLC method, according to the protocol of Morel et al. (25).Free MDA Evaluation
HPLC procedure. MDA quantification was performed according to a method described previously (11). The HPLC system (LDC-Milton Roy) was equipped with a spherogel-TSK G1000 PW size exclusion column (7.5 mm ID × 30 cm; Cluzeau, France). The eluant was composed of 0.1 M disodium phosphate buffer, pH 8, at a flow rate of 1 ml/min, at ambient temperature. The absorbance was monitored at 267 nm, and the sensitivity was set at 0.05 absorbance units full scale. The injections were performed by an automatic injector (LDC Promis) set at a volume of 250 µl. The data were recorded and integrated by a CI 3000 LDC integrator.
Preparation of free MDA standard. Ten microliters of 1,1,3,3-tetramethoxypropane were hydrolyzed in 10 ml of 0.1 N HCl for 5 min in boiling water. This solution was then diluted 1,000 times in 0.01 M Na2HPO4 buffer, pH 7.45, corresponding to a 6 µM MDA solution. The concentration of MDA in samples was calculated by using a standard curve of free MDA.
Preparation of the samples for HPLC analysis. Free MDA was quantified from culture medium. Culture media were collected, and hepatocytes were washed twice with 0.01 M phosphate buffer, pH 7.45. They were resuspended in 1 ml of the same buffer. The cells were lysed by use of an ultrasonic homogenizer. Culture media were filtered through a 500-Da membrane ultrafilter (Millipore, Yvelines, France) in a 10-ml Amicon cell pressurized at 4 bars with nitrogen gas. The filtrate was used for the HPLC procedure. All experiments were performed at least on triplicate cultures. We determined protein content on cell homogenates according to the Bradford reaction (5) using the Bio-Rad reagent, BSA as standard, and a Cobas-Bio automatic analyzer.
Each culture supplemented with both lactate and Fe-NTA was compared with control cultures supplemented with Fe-NTA alone (representing 100%).Statistical Analysis
The results are given as means ± SE of our experiments. We chose a nonparametric test to reveal significant differences between trials with and without lactate. The Mann-Whitney test was used instead of an ANOVA on ranks because the effect of lactate concentration for each experiment had to be compared with its own control sample specific to the experiment of that day. We have not provided the number of assays performed because the number was never the same. Nevertheless, there were at least five with a significant result when we concluded. P < 0.01 was chosen as significance level.| |
RESULTS |
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TOP
ABSTRACT
INTRODUCTION
MATERIALS AND METHODS
RESULTS
DISCUSSION
REFERENCES
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Free Radical Scavenging Activity of Lactate Toward ·OH and
O2·
Scavenging of ·OH.
Assuming that the signal intensity in the controls without lactate
corresponds to 100% DMPO-·OH formation, Fig.
1A shows that lactate addition
to aqueous solution at final concentrations of 10, 15, 30, and 60 mM
was associated with a decrease in EPR signal. This decrease was due to
a scavenging activity of lactate toward the ·OH that was
concentration dependent. In samples containing lactate in aqueous
solution, the EPR signal values were, respectively, 64% (10 mM),
52.5% (15 mM), 46% (30 mM), and 38% (60 mM). Figure 1B
shows the effect of lactate dissolved in plasma. Because plasma alone
exhibited a scavenging activity toward ·OH, plasma without lactate
was taken for reference 100%. Addition of lactate dissolved in plasma
reduced the EPR signal intensity only at high concentration levels (30 and 60 mM). EPR signal values were, respectively, 75% (30 mM) and
53.5% (60 mM) of the control value.
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Scavenging of O2·.
As previously stated, controls without lactate correspond to 100%
DMPO-OOH· adduct. Addition of lactate in aqueous solution caused a
decrease in DMPO-OOH· adduct as shown in Fig.
2A, indicating a scavenging
effect of lactate (1, 10, 15, 30, and 60 mM) toward superoxide
radicals. EPR signal intensities were, respectively, 57% (1 mM),
25.5% (10 mM), 23.5% (15 mM), 12.5% (30 mM), and 11.5% (60 mM) of
control value. A scavenging effect was also observed with lactate in
plasma (Fig. 2B). EPR signal intensities were, respectively,
86.5% (1 mM), 72% (10 mM), 54% (30 mM), 64% (15 mM), and 26% (60 mM). DMPO-OOH· adduct at 100% represented the plasma control.
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Lack of Lactate Effect to Inhibit Linoleic Acid Autoxidation in Micelles
Conjugated dienes resulting from the spontaneous autoxidation of linoleic acid (at pH 7.4 and temperature 37°C) were measured by their absorbance at 234 nm (Fig. 3). The level of conjugated dienes increased rapidly to reach a maximum at 20 h and then remained constant. As shown in Fig. 3, addition of lactate at 1, 10, and 15 mM was without any effect on the time course of the formation of conjugated dienes. Data for lactate at 30 and 60 mM are not presented in Fig. 3, but no inhibitory effect was observed even for these concentrations.
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Antioxidant Effect of Lactate Toward Oxidative Stress Induced in Hepatocyte Cultures
Addition of Fe-NTA to hepatocyte cultures for 4 h induced a large increase in the level of free MDA released in culture medium (25). MDA is commonly used as a marker of lipid peroxidation. The level of MDA in the iron-treated hepatocyte cultures was taken as the reference of 100% free MDA production. Addition of lactate reduced the amount of MDA, and the decrease was concentration dependent, as shown in Fig. 4. This antioxidant activity was significant with 15, 30, and 60 mM lactate. MDA values expressed in percentage of controls (100%) were, respectively, 86% (15 mM), 58.5% (30 mM), and 49% (60 mM).
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DISCUSSION |
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TOP
ABSTRACT
INTRODUCTION
MATERIALS AND METHODS
RESULTS
DISCUSSION
REFERENCES
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The present study, using three different in vitro models at physiological pH, provides evidence that the lactate ion may act as a good antioxidant.
The first model consisted of EPR experiments to determine the
scavenging activity of lactate toward free radicals such as ·OH and
O2·. Our data indicated that EPR signals were
reduced for both ·OH and O2· by lactate in
aqueous solution and in plasma. These results confirmed that lactate
scavenged ·OH and O2·. Scavenging of ·OH by
lactate was previously reported by Anbar and Neta (2). For
these authors, the rate constant of reaction was calculated as 4.8 × 109 M1 · s1 at pH 9, a value very close to the rate constant of reaction evaluated in this
study (6.9 × 109 M1 · s1 when lactate was dissolved in aqueous solution and
3.8 × 109 M1 · s1
when lactate was dissolved in plasma). According to Herz et al. (21), this value demonstrates the powerful ·OH
scavenging ability of lactate. Indeed, the rate constant of reaction of
lactate was greater than that of mannitol (which is commonly referred
to as an efficient ·OH scavenger), glucose, and ethanol but less than that of catalase and ascorbic acid.
No information is currently available concerning the scavenging
activity of the well-known antioxidant agents toward
O2·. To our knowledge, this study is also the first
report of the ability of lactate to scavenge O2·.
Although O2· is considered to be a poorly reactive
radical, O2· formation is a major factor in oxygen
toxicity because it leads to the formation of toxic species such as
H2O2 and ·OH. The free radical scavenging
effect of lactate was less marked in plasma than in aqueous solution.
In fact, plasma alone exerted an antioxidant effect (data not shown)
because of the presence of well-known antioxidant plasma agents such as
vitamin C (55 µM), vitamin E (14-35 µM), glucose (4.5 mM), and
uric acid (0.25-0.45 µM) (17). Thus lactate action
at low concentrations (1-15 mM) was partly masked by the effect of
these antioxidants. At high lactate levels such as 30 and 60 mM,
lactate action was increased. It should be noted that, because the
plasma concentration of these antioxidants varies with the nutritional
status, all experiments were performed with the same plasma sample.
The second model, based on linoleic acid autoxidation in micelles (10), showed that lactate did not inhibit lipid peroxidation. No induction period was observed. Indeed, in a micelle system, the autoxidation process involves lipid radicals such as peroxyl radical (ROO·) and alkoxyl radical (RO·) (24). Scavengers (e.g., tocopherol) of these radicals inhibit the autoxidation reaction. Thus it can be deduced that lactate did not scavenge lipid radicals.
The third model was a cellular model using hepatocytes in culture.
Oxidative stress was induced in hepatocyte culture by addition of
Fe-NTA. In this system, lactate was able to inhibit lipid peroxidation. This discrepancy between a cellular antilipoperoxidant effect of
lactate and its ineffectiveness to prevent lipid peroxidation in
micelles could be explained by the property of lactate to scavenge radicals such as ·OH and O2· but not lipid
radicals. In hepatocytes, ·OH and O2· are
generated by the Fenton and Haber-Weiss reactions (14). These radicals then initiate membrane lipid peroxidation. Thus lactate,
by eliminating ·OH and O2·, prevented lipid
peroxidation. In other words, lactate acted at the initiation step of
lipid peroxidation but not at the propagation step, which involves
lipid radicals. Such findings are not surprising because lactate is not
liposoluble. Vitamin C, a well-known antioxidant agent, reacts rapidly
with O2· and ·OH but not with peroxyl radical. In
contrast, the well-known liposoluble vitamin E is a powerful scavenger
of lipid radicals (8).
The antioxidant effect of lactate was concentration dependent. These findings are important to further our understanding of the effect of lactate on the free radicals produced during exercise, because plasma and muscular lactate levels increase with exercise intensity. Plasma lactate concentration may rise from 1 mM to 10 mM at maximal oxygen consumption and to 15 mM, possibly 30 mM, during supramaximal exercise (27). These concentrations were therefore chosen for the study. Also, 30 and 60 mM correspond to the lactate concentrations that could be found in the active muscles after a very brief and intensive exercise (22, 29). These high concentrations of lactate might protect cells from free radical damage during exercise.
Some data in the literature have indicated the protective effect of lactate ion. Using 23Na and 31P NMR, Yanagida et al. (32) showed that lactate can protect rat heart from ·OH damage. In another NMR study of biofluids, Herz et al. (21) concluded that consumption of ·OH by lactate may serve to protect alternative biofluid components against ROS-mediated damage in vivo. Moreover, addition of lactate to ischemic reperfused hearts was found to prevent decline in the enzymatic defense system against oxygen toxicity (13).
The antioxidant effect of lactate thus seems undebatable. However,
because a relationship was found during maximal incremental exercise
between plasma MDA and lactate concentration, Lovlin et al.
(23) incriminated lactate as a promoting factor of
exercise-induced oxidative stress. In fact, lactate produced during
exercise is always associated with acidosis, which can act as a
prooxidant agent (4, 6) by three mechanisms.
First, during acidosis, increase in H+ concentration
accelerates the rate of dismutation of O2· to
H2O2, which can react with Fe2+ and
generate the highly toxic ·OH. Second, during acidosis, increase in
H+ converts O2· to the more reactive
and more lipid soluble hydroperoxyl radical HO2. Third,
another possible effect of tissue acidosis is to stimulate free radical
generation by increasing dissociation of protein-bound iron, as
originally suggested by Bernheim (4). Thus it seems more
likely that the oxidative stress noted in the study by Lovlin et al.
(23) was more in relationship with acidosis than with lactate alone. Many previous results support this hypothesis
(6, 16), showing that lactic acid and not
lactate ion alone promotes lipoperoxidation.
The mechanisms underlying the antioxidant effect of lactate have yet to be elucidated. Also using EPR experiments, Anbar and Neta (2) reported a direct scavenging activity of lactate toward ·OH. Nevertheless, an indirect antioxidant effect of lactate was also assumed by Herz et al. (21). According to these authors, the consumption of ·OH by lactate generates pyruvate, an antioxidant agent that is also able to scavenge H2O2 and ·OH by its decomposition into acetate and CO2. Because hepatocyte culture is a biological model that contains the lactic dehydrogenase enzyme, the transformation of lactate into pyruvate was possible. Thus this indirect mechanism cannot be totally excluded in the present study to explain the reduction of MDA when lactate was present in culture medium at 15, 30, and 60 mM.
This study nevertheless adds further information about this subject. It
clearly demonstrates for the first time that lactate is also able to
directly scavenge O2·, a potent oxygen reactive
species that is produced in large quantity during exercise
(3).
In conclusion, the results of the present study contribute to the
recent literature on the beneficial aspect of lactate by suggesting
that lactate ion can be considered as a potential antioxidant agent and
by demonstrating that lactate ion, in vitro, is not prooxidant. We
showed that lactate was able to scavenge both ·OH and
O2·, in vitro, with the effect toward
O2· being predominant. No scavenging effect of
lactate was observed toward lipid radicals. This antioxidant capacity
of lactate is very important regarding exercise performance. By
scavenging O2·, the lactate ion may limit the high
exercise-induced increase in the production of ROS. By scavenging both
O2· and ·OH, lactate may limit the initiation step of
lipid peroxidation and thus protect cells against oxidative damage. The
precise mechanisms remain to be elucidated.
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ACKNOWLEDGEMENTS |
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We thank C. Stott Carmeni for technical assistance and M. Benanni-Dosse for statistical assistance.
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FOOTNOTES |
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Address for reprint requests and other correspondence: C. Groussard, Laboratoire de Physiologie et de Biomécanique de l'Exercice Musculaire, UFRAPS Rennes 2, Ave. Charles Tillon, CS 24414, 35044 Rennes Cedex, France (E-mail: carole.groussard{at}uhb.fr).
The costs of publication of this article were defrayed in part by the payment of page charges. The article must therefore be hereby marked "advertisement" in accordance with 18 U.S.C. §1734 solely to indicate this fact.
Received 15 June 1999; accepted in final form 9 March 2000.
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REFERENCES |
|---|
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TOP
ABSTRACT
INTRODUCTION
MATERIALS AND METHODS
RESULTS
DISCUSSION
REFERENCES
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|---|
1.
Alessio, HM,
Goldfarb AH,
and
Cutler RG.
MDA content increases in fast- and slow-twitch skeletal muscle with intensity of exercise in a rat.
Am J Physiol
24:
C874-C877,
1988.
2.
Anbar, M,
and
Neta P.
A compilation of specific biomolecular rate constants for the reactions of hydrated electrons, hydrogen atoms and hydroxyl radicals with organic compounds in aqueous solution.
Int J Appl Radiat Isotopes
18:
493-523,
1967.
3.
Astrand, PO,
and
Rodahl K.
Textbook of Work Physiology: Physiological Bases of Exercise. New York: McGraw-Hill, 1986.
4.
Bernheim, F.
Biochemical implications of pro-oxidants and antioxidants.
Rad Res
Suppl:
33-43,
1963.
5.
Bradford, MM.
A rapid and sensitive method for quantitation of microgram quantities of protein utilizing the principle of protein dye binding.
Anal Biochem
72:
248-254,
1976[ISI][Medline].
6.
Bralet, J,
Bouvier C,
Schreiber L,
and
Boquillon M.
Effect of acidosis on lipid peroxidation in brain slices.
Brain Res
539:
175-177,
1991[ISI][Medline].
7.
Buettner, GR,
and
Mason RP.
Spin trapping methods for detecting superoxide and hydroxyl free radicals in vitro and in vivo.
In: Methods in Enzymology, edited by Packer L,
and Glazer AN.. San Diego, CA: Academic, 1990, p. 127-133.
8.
Burton, GW,
and
Ingold KU.
Vitamin E as an in vitro and in vivo antioxidant.
Ann NY Acad Sci
570:
7-22,
1989[Abstract].
9.
Chimi, H,
Cillard J,
Cillard P,
and
Rahamani M.
Peroxyl and hydroxyl radical scavenging activity of some natural phenolic antioxidants.
J Am Oil Chem Soc
68:
307-312,
1991.
10.
Cillard, J,
and
Cillard P
Cormier M, and L. Girre. Alpha-tocopherol prooxidant effect in aqueous media: increased autoxidation rate of linoleic acid.
J Am Oil Chem Soc
57:
252-255,
1980.
11.
Csallany, AS,
Guan DM,
Manwaring JD,
and
Addis PB.
Free malonaldehyde determination in tissues by high-performance liquid chromatography.
Anal Biochem
142:
277-283,
1984[ISI][Medline].
12.
Davies, KJA,
Quintanilha AT,
Brooks GA,
and
Packer L.
Free radicals and tissue damage produced by exercise.
Biochem Biophys Res Commun
107:
1198-1205,
1982[ISI][Medline].
13.
De Groot, MJM,
Van Helden MAB,
De Jong YF,
Coumans WA,
and
Van Der Vusse GJ.
The influence of lactate, pyruvate and glucose as exogenous substrates on free radical defense mechanisms in isolated rat hearts during ischaemia and reperfusion.
Mol Cell Biochem
146:
147-155,
1995[ISI][Medline].
14.
Dianzani, MU.
The role of free radicals in liver damage.
Proc Nutr Soc
46:
43-52,
1987[ISI][Medline].
15.
Dillard, CJ,
Litov RE,
Savin WM,
Dumelin EE,
and
Tappel AL.
Effect of exercise, vitamin E, and ozone on pulmonary function and lipid peroxidation.
J Appl Physiol
45:
927-932,
1978
16.
Fauconneau, B,
Tallineau C,
Huguet F,
Guillard O,
and
Piriou A.
Iron- and lactic acid-induced lipid peroxidation in rat kidney homogenates and slices.
Biochem Mol Biol Int
31:
421-427,
1993[ISI][Medline].
17.
Frei, B.
Natural Antioxidant in Human Health and Disease. London: Academic Press, 1994.
18.
Fridovich, I.
Quantitative aspect of the production of superoxide anion radical by milk xanthine oxidase.
J Biol Chem
245:
4053-4057,
1970
19.
Gohil, K,
Viguie C,
Stanley WC,
Brooks GA,
and
Packer L.
Blood glutathione oxidation during human exercise.
J Appl Physiol
6:
115-119,
1988.
20.
Guguen, C,
Guillouzo A,
Boinonard M,
Le Cam A,
and
Bourel M.
Etude ultrastructurale de monocouches d'hépatocytes de rat adulte cultivé en présence d'hémisuccinate d'hydrocortisone.
Biol Gastro Enterol
8:
223-231,
1975.
21.
Herz, H,
Blake DR,
and
Grootveld M.
Multicomponent investigations of the hydrogen peroxide- and hydroxyl radical-scavenging antioxidant capacities of biofluids: the roles of exogenous pyruvate and lactate.
Free Radic Res
26:
19-35,
1997[ISI][Medline].
22.
Jacobs, I,
Tesch PA,
Bar-Or O,
Karlsson J,
and
Dotan R.
Lactate in human skeletal muscle after 10 and 30 s of supramaximal exercise.
J Appl Physiol
55:
365-367,
1983
23.
Lovlin, R,
Cottle W,
Pyke I,
Kavanagh M,
and
Belcastro AN.
Are indices of free radical damage related to exercise intensity?
Eur J Appl Physiol
56:
313-316,
1987.
24.
Mead, JM.
Free radical mechanisms of lipid damage and consequences for cellular membranes.
In: Free Radicals in Biology, edited by Pryor WA.. London: Academic Press, 1976, p. 51-68.
25.
Morel, I,
Lescoat G,
Cillard J,
Padeloup N,
Bissot P,
and
Cillard P.
Kinetic evaluation of free malondialdehyde and enzyme leakage as indices of iron damage in rat hepatocyte cultures: involvement of free radicals.
Biochem Pharmacol
39:
1647-1655,
1990[ISI][Medline].
26.
Nagy, IZS,
and
Floyd RA.
Hydroxyl free radical reactions with amino acids and proteins studied by electron spin resonance spectroscopy and spin trapping.
Biochim Biophys Acta
790:
238-250,
1984[Medline].
27.
Osnes, J,
and
Hermansen L.
Acid base balance after maximal exercise of short duration.
J Appl Physiol
3:
59-63,
1972.
28.
Rehncrona, S,
Hauge HN,
and
Siesjö BK.
Enhancement of iron-catalysed free radical formation by acidosis in brain homogenates: differences in effect by lactic acid and CO2.
J Cereb Blood Flow Metab
9:
65-70,
1989[ISI][Medline].
29.
Sahlin, K,
and
Ren JM.
Relationship of contraction capacity to metabolic changes during recovery from fatiguing contraction.
J Appl Physiol
67:
648-657,
1989
30.
Siesjo, BK,
Bendek G,
Koide T,
Westerberg E,
and
Wieloch T.
Influence of acidosis on lipid peroxidation in brain tissues in vitro.
J Cereb Blood Flow Metab
5:
253-258,
1985[ISI][Medline].
31.
White, GP,
and
Jacobs A.
Iron uptake by Chang liver cells from transferrin, nitrilotriacetate and citrate complexes: the effect of iron-loading and chelation with desferrioxamine.
Biochim Biophys Acta
543:
217-225,
1978[Medline].
32.
Yanagida, S,
Luo CS,
Doyle M,
Pohost GM,
and
Pike MM.
Nuclear magnetic resonance studies of cationic and energic alterations with oxidant stress in the perfused heart: modulation with pyruvate and lactate.
Circ Res
77:
773-783,
1995
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), with 1 mM lactate (
), with 10 mM lactate (
),
and with 15 mM lactate (
). Results obtained with lactate at 30 and
60 mM are not presented. No effect was noted at these concentrations.
