... Tepp, Natalja Timohhina, Vladimir Chekulayev, Igor Shevchuk, Tuuli Kaambre and Valdur Saks ..... more ... Tepp, Natalja Timohhina, Vladimir Chekulayev, Igor Shevchuk, Tuuli Kaambre and Valdur Saks .....421 ... Katarzyna Augoff, Adam Kolondra, Anna Chorzalska,Agnieszka Lach, Krzysztof Grabowski and Aleksander F ...
American journal of physiology. Endocrinology and metabolism, 2000
The effects of endurance training on lactate transport capacity remain controversial. This study ... more The effects of endurance training on lactate transport capacity remain controversial. This study examined whether endurance training 1) alters lactate transport capacity, 2) can protect against exhaustive exercise-induced lactate transport alteration, and 3) can modify heart and oxidative muscle monocarboxylate transporter 1 (MCT1) content. Forty male Wistar rats were divided into control (C), trained (T), exhaustively exercised (E), and trained and exercised (TE) groups. Rats in the T and TE groups ran on a treadmill (1 h/day, 5 days/wk at 25 m/min, 10% incline) for 5 wk; C and E were familiarized with the exercise task for 5 min/day. Before being killed, E and TE rats underwent exhaustive exercise (25 m/min, 10% grade), which lasted 80 and 204 min, respectively (P < 0.05). Although lactate transport measurements (zero-trans) did not differ between groups C and T, both E and TE groups presented an apparent loss of protein saturation properties. In the trained groups, MCT1 conten...
American journal of physiology. Endocrinology and metabolism, 2000
To evaluate the effects of endurance training on the expression of monocarboxylate transporters (... more To evaluate the effects of endurance training on the expression of monocarboxylate transporters (MCT) in human vastus lateralis muscle, we compared the amounts of MCT1 and MCT4 in total muscle preparations (MU) and sarcolemma-enriched (SL) and mitochondria-enriched (MI) fractions before and after training. To determine if changes in muscle lactate release and oxidation were associated with training-induced changes in MCT expression, we correlated band densities in Western blots to lactate kinetics determined in vivo. Nine weeks of leg cycle endurance training [75% peak oxygen consumption (VO(2 peak))] increased muscle citrate synthase activity (+75%, P < 0.05) and percentage of type I myosin heavy chain (+50%, P < 0.05); percentage of MU lactate dehydrogenase-5 (M4) isozyme decreased (-12%, P < 0.05). MCT1 was detected in SL and MI fractions, and MCT4 was localized to the SL. Muscle MCT1 contents were consistent among subjects both before and after training; in contrast, MC...
Journal of applied physiology (Bethesda, Md. : 1985), 1998
We investigated in rats the effect of 4 wk of hypodynamia on the respiration of mitochondria isol... more We investigated in rats the effect of 4 wk of hypodynamia on the respiration of mitochondria isolated from four distinct muscles [soleus, extensor digitorum longus, tibial anterior, and gastrocnemius (Gas)] and from subsarcolemmal (SS) and intermyofibrillar (IMF) regions of mixed hindlimb muscles that mainly contained the four cited muscles. With pyruvate plus malate as respiratory substrate, 4 wk of hindlimb suspension produced an 18% decrease in state 3 respiration for IMF mitochondria compared with those in the control group (P < 0.05). The SS mitochondria state 3 were not significantly changed. Concerning the four single muscles, the mitochondrial respiration was significantly decreased in the Gas muscle, which showed a 59% decrease in state 3 with pyruvate + malate (P < 0.05). The other muscles presented no significant decrease in respiratory rate in comparison with the control group. With succinate + rotenone, there was no significant difference in the respiratory rate c...
Comptes rendus des séances de la Société de biologie et de ses filiales, 1995
Skeletal muscle sarcolemmal vesicles from control (C) and hindlimb suspended (S) rats were used t... more Skeletal muscle sarcolemmal vesicles from control (C) and hindlimb suspended (S) rats were used to investigate the effect of unweighting on the lactate transporter activity. Sarcolemmal preparations were not different between the two groups. The efficiency of 4 weeks of hindlimb suspension was confirmed by a 40% decrease of citrate synthetase activity and a shift towards faster myosin isoforms in soleus muscle. The time course of 1 mM lactate uptake showed that the equilibrium was reached faster in group C (20 s) than in group S (40 s). The initial rate of 1 mM of lactate uptake decreased significantly (p < 0.05) after 4 weeks of hindlimb suspension. The initial rate of 50 mM lactate uptake did not differ significantly between the two groups. We conclude that 4 weeks of unweighting decreases significantly the skeletal muscle sarcolemmal lactate transport activity in rats. This result suggests that the level of physical activity probably plays a role on lactate transport regulatio...
We investigated the effects of a single bout of non-exhaustive exercise (25 m x min(-1), 10% grad... more We investigated the effects of a single bout of non-exhaustive exercise (25 m x min(-1), 10% grade, for 30 min) on the initial rates of lactate uptake in rat skeletal muscle sarcolemmal vesicles and the monocarboxylate transporter 1 (MCT1) content in isolated hindlimb muscles in relation to the exercise-induced oxidative stress. The exercise led to a decrease in red gastrocnemius and red vastus lateralis muscle glycogen content by 74% and 83%, respectively, and an increase in blood lactate concentration from 1.67 +/- 0.15 to 3.44 +/- 0.47 mM (p &lt; 0.05). Initial rates of lactate uptake were measured in zero-trans conditions, at pH 7.4, for 1, 10, 30 and 100 mM external lactate concentrations. Lactate transport capacity was significantly decreased at 1 mM in the exercised group (p &lt; 0.05), while a non-significant trend towards an increase was observed at 10, 30 and 100 mM. We failed to obtain any change in soleus, red tibialis anterior and white gastrocnemius muscle MCT1 content (p&gt;0.05), and no evidence of exercise-induced oxidative stress in terms of muscle malondialdehyde content and glutathione peroxidase and superoxide dismutase activities was observed after the 30 min exercise bout. These results indicate that a single bout of submaximal exercise, which did not induce an increase in muscle MCT1 content and apparent oxidative stress, decreased lactate transport capacity at low physiological concentration. Although the changes are small and independent of a MCT1-facilitated lactate transport regulation, we suggest that another MCT isoform with different kinetic properties from MCT1 could be present in the sarcolemma and responsible for lactate exchange alterations.
Proceedings of the National Academy of Sciences, 1999
To evaluate the potential role of mitochondrial lactate dehydrogenase (LDH) in tissue lactate cle... more To evaluate the potential role of mitochondrial lactate dehydrogenase (LDH) in tissue lactate clearance and oxidation in vivo, isolated rat liver, cardiac, and skeletal muscle mitochondria were incubated with lactate, pyruvate, glutamate, and succinate. As well, ␣-cyano-4-hydroxycinnamate (CINN), a known monocarboxylate transport inhibitor, and oxamate, a known LDH inhibitor were used. Mitochondria readily oxidized pyruvate and lactate, with similar state 3 and 4 respiratory rates, respiratory control (state 3͞state 4), and ADP͞O ratios. With lactate or pyruvate as substrates, ␣-cyano-4-hydroxycinnamate blocked the respiratory response to added ADP, but the block was bypassed by addition of glutamate (complex I-linked) and succinate (complex II-linked) substrates. Oxamate increased pyruvate (Ϸ10-40%), but blocked lactate oxidation. Gel electrophoresis and electron microscopy indicated LDH isoenzyme distribution patterns to display tissue specificity, but the LDH isoenzyme patterns in isolated mitochondria were distinct from those in surrounding cell compartments. In heart, LDH-1 (H4) was concentrated in mitochondria whereas LDH-5 (M4) was present in both mitochondria and surrounding cytosol and organelles. LDH-5 predominated in liver but was more abundant in mitochondria than elsewhere. Because lactate exceeds cytosolic pyruvate concentration by an order of magnitude, we conclude that lactate is the predominant monocarboxylate oxidized by mitochondria in vivo. Mammalian liver and striated muscle mitochondria can oxidize exogenous lactate because of an internal LDH pool that facilitates lactate oxidation.
Medicine & Science in Sports & Exercise, 1996
We investigated NaHCO3 infusion effects on plasma lactate removal by forearm muscles and performa... more We investigated NaHCO3 infusion effects on plasma lactate removal by forearm muscles and performance during intensive leg exercise. Seven subjects performed the force-velocity (FV) test with placebo and NaHCO3 (2 mEq.min-1) with a double-blind crossover protocol. Blood samples for arterial ([LA]A) and venous ([LA]V) lactate determinations were taken 1) at rest before infusion, and 2, 6, 10, 14, 18, and 22 min following its start; and 2) at the end of each exercise bout. The arteriovenous difference ([LA]A-V) was determined for each sampling. NaHCO3 significantly increased arterial bicarbonate concentration and pH during rest (P &amp;amp;lt; 0.001; P &amp;amp;lt; 0.001) and the FV test (P &amp;amp;lt; 0.001; P &amp;amp;lt; 0.05). During the test, [LA]A and [LA]V were significantly higher with NaHCO3 (P &amp;amp;lt; 0.05, P &amp;amp;lt; 0.001). At test onset, [LA]A-V became positive and increased until the braking force of 6 kg, with NaHCO3 and placebo, with values significantly lower for NaHCO3 (P &amp;amp;lt; 0.001). Peak anaerobic power (Wanae, peak) and the corresponding braking force (Fmax) were also determined. Fmax was significantly increased with NaHCO3 (P &amp;amp;lt; 0.001). In conclusion, the increasing rise in [LA]A and [LA]V induced by NaHCO3 may be partly explained by a decreased rate of lactate uptake by forearm skeletal muscles. NaHCO3 did not improve Wanae, peak, but improved Fmax, thus increasing FV duration.
... Tepp, Natalja Timohhina, Vladimir Chekulayev, Igor Shevchuk, Tuuli Kaambre and Valdur Saks ..... more ... Tepp, Natalja Timohhina, Vladimir Chekulayev, Igor Shevchuk, Tuuli Kaambre and Valdur Saks .....421 ... Katarzyna Augoff, Adam Kolondra, Anna Chorzalska,Agnieszka Lach, Krzysztof Grabowski and Aleksander F ...
American journal of physiology. Endocrinology and metabolism, 2000
The effects of endurance training on lactate transport capacity remain controversial. This study ... more The effects of endurance training on lactate transport capacity remain controversial. This study examined whether endurance training 1) alters lactate transport capacity, 2) can protect against exhaustive exercise-induced lactate transport alteration, and 3) can modify heart and oxidative muscle monocarboxylate transporter 1 (MCT1) content. Forty male Wistar rats were divided into control (C), trained (T), exhaustively exercised (E), and trained and exercised (TE) groups. Rats in the T and TE groups ran on a treadmill (1 h/day, 5 days/wk at 25 m/min, 10% incline) for 5 wk; C and E were familiarized with the exercise task for 5 min/day. Before being killed, E and TE rats underwent exhaustive exercise (25 m/min, 10% grade), which lasted 80 and 204 min, respectively (P < 0.05). Although lactate transport measurements (zero-trans) did not differ between groups C and T, both E and TE groups presented an apparent loss of protein saturation properties. In the trained groups, MCT1 conten...
American journal of physiology. Endocrinology and metabolism, 2000
To evaluate the effects of endurance training on the expression of monocarboxylate transporters (... more To evaluate the effects of endurance training on the expression of monocarboxylate transporters (MCT) in human vastus lateralis muscle, we compared the amounts of MCT1 and MCT4 in total muscle preparations (MU) and sarcolemma-enriched (SL) and mitochondria-enriched (MI) fractions before and after training. To determine if changes in muscle lactate release and oxidation were associated with training-induced changes in MCT expression, we correlated band densities in Western blots to lactate kinetics determined in vivo. Nine weeks of leg cycle endurance training [75% peak oxygen consumption (VO(2 peak))] increased muscle citrate synthase activity (+75%, P < 0.05) and percentage of type I myosin heavy chain (+50%, P < 0.05); percentage of MU lactate dehydrogenase-5 (M4) isozyme decreased (-12%, P < 0.05). MCT1 was detected in SL and MI fractions, and MCT4 was localized to the SL. Muscle MCT1 contents were consistent among subjects both before and after training; in contrast, MC...
Journal of applied physiology (Bethesda, Md. : 1985), 1998
We investigated in rats the effect of 4 wk of hypodynamia on the respiration of mitochondria isol... more We investigated in rats the effect of 4 wk of hypodynamia on the respiration of mitochondria isolated from four distinct muscles [soleus, extensor digitorum longus, tibial anterior, and gastrocnemius (Gas)] and from subsarcolemmal (SS) and intermyofibrillar (IMF) regions of mixed hindlimb muscles that mainly contained the four cited muscles. With pyruvate plus malate as respiratory substrate, 4 wk of hindlimb suspension produced an 18% decrease in state 3 respiration for IMF mitochondria compared with those in the control group (P < 0.05). The SS mitochondria state 3 were not significantly changed. Concerning the four single muscles, the mitochondrial respiration was significantly decreased in the Gas muscle, which showed a 59% decrease in state 3 with pyruvate + malate (P < 0.05). The other muscles presented no significant decrease in respiratory rate in comparison with the control group. With succinate + rotenone, there was no significant difference in the respiratory rate c...
Comptes rendus des séances de la Société de biologie et de ses filiales, 1995
Skeletal muscle sarcolemmal vesicles from control (C) and hindlimb suspended (S) rats were used t... more Skeletal muscle sarcolemmal vesicles from control (C) and hindlimb suspended (S) rats were used to investigate the effect of unweighting on the lactate transporter activity. Sarcolemmal preparations were not different between the two groups. The efficiency of 4 weeks of hindlimb suspension was confirmed by a 40% decrease of citrate synthetase activity and a shift towards faster myosin isoforms in soleus muscle. The time course of 1 mM lactate uptake showed that the equilibrium was reached faster in group C (20 s) than in group S (40 s). The initial rate of 1 mM of lactate uptake decreased significantly (p < 0.05) after 4 weeks of hindlimb suspension. The initial rate of 50 mM lactate uptake did not differ significantly between the two groups. We conclude that 4 weeks of unweighting decreases significantly the skeletal muscle sarcolemmal lactate transport activity in rats. This result suggests that the level of physical activity probably plays a role on lactate transport regulatio...
We investigated the effects of a single bout of non-exhaustive exercise (25 m x min(-1), 10% grad... more We investigated the effects of a single bout of non-exhaustive exercise (25 m x min(-1), 10% grade, for 30 min) on the initial rates of lactate uptake in rat skeletal muscle sarcolemmal vesicles and the monocarboxylate transporter 1 (MCT1) content in isolated hindlimb muscles in relation to the exercise-induced oxidative stress. The exercise led to a decrease in red gastrocnemius and red vastus lateralis muscle glycogen content by 74% and 83%, respectively, and an increase in blood lactate concentration from 1.67 +/- 0.15 to 3.44 +/- 0.47 mM (p &lt; 0.05). Initial rates of lactate uptake were measured in zero-trans conditions, at pH 7.4, for 1, 10, 30 and 100 mM external lactate concentrations. Lactate transport capacity was significantly decreased at 1 mM in the exercised group (p &lt; 0.05), while a non-significant trend towards an increase was observed at 10, 30 and 100 mM. We failed to obtain any change in soleus, red tibialis anterior and white gastrocnemius muscle MCT1 content (p&gt;0.05), and no evidence of exercise-induced oxidative stress in terms of muscle malondialdehyde content and glutathione peroxidase and superoxide dismutase activities was observed after the 30 min exercise bout. These results indicate that a single bout of submaximal exercise, which did not induce an increase in muscle MCT1 content and apparent oxidative stress, decreased lactate transport capacity at low physiological concentration. Although the changes are small and independent of a MCT1-facilitated lactate transport regulation, we suggest that another MCT isoform with different kinetic properties from MCT1 could be present in the sarcolemma and responsible for lactate exchange alterations.
Proceedings of the National Academy of Sciences, 1999
To evaluate the potential role of mitochondrial lactate dehydrogenase (LDH) in tissue lactate cle... more To evaluate the potential role of mitochondrial lactate dehydrogenase (LDH) in tissue lactate clearance and oxidation in vivo, isolated rat liver, cardiac, and skeletal muscle mitochondria were incubated with lactate, pyruvate, glutamate, and succinate. As well, ␣-cyano-4-hydroxycinnamate (CINN), a known monocarboxylate transport inhibitor, and oxamate, a known LDH inhibitor were used. Mitochondria readily oxidized pyruvate and lactate, with similar state 3 and 4 respiratory rates, respiratory control (state 3͞state 4), and ADP͞O ratios. With lactate or pyruvate as substrates, ␣-cyano-4-hydroxycinnamate blocked the respiratory response to added ADP, but the block was bypassed by addition of glutamate (complex I-linked) and succinate (complex II-linked) substrates. Oxamate increased pyruvate (Ϸ10-40%), but blocked lactate oxidation. Gel electrophoresis and electron microscopy indicated LDH isoenzyme distribution patterns to display tissue specificity, but the LDH isoenzyme patterns in isolated mitochondria were distinct from those in surrounding cell compartments. In heart, LDH-1 (H4) was concentrated in mitochondria whereas LDH-5 (M4) was present in both mitochondria and surrounding cytosol and organelles. LDH-5 predominated in liver but was more abundant in mitochondria than elsewhere. Because lactate exceeds cytosolic pyruvate concentration by an order of magnitude, we conclude that lactate is the predominant monocarboxylate oxidized by mitochondria in vivo. Mammalian liver and striated muscle mitochondria can oxidize exogenous lactate because of an internal LDH pool that facilitates lactate oxidation.
Medicine & Science in Sports & Exercise, 1996
We investigated NaHCO3 infusion effects on plasma lactate removal by forearm muscles and performa... more We investigated NaHCO3 infusion effects on plasma lactate removal by forearm muscles and performance during intensive leg exercise. Seven subjects performed the force-velocity (FV) test with placebo and NaHCO3 (2 mEq.min-1) with a double-blind crossover protocol. Blood samples for arterial ([LA]A) and venous ([LA]V) lactate determinations were taken 1) at rest before infusion, and 2, 6, 10, 14, 18, and 22 min following its start; and 2) at the end of each exercise bout. The arteriovenous difference ([LA]A-V) was determined for each sampling. NaHCO3 significantly increased arterial bicarbonate concentration and pH during rest (P &amp;amp;lt; 0.001; P &amp;amp;lt; 0.001) and the FV test (P &amp;amp;lt; 0.001; P &amp;amp;lt; 0.05). During the test, [LA]A and [LA]V were significantly higher with NaHCO3 (P &amp;amp;lt; 0.05, P &amp;amp;lt; 0.001). At test onset, [LA]A-V became positive and increased until the braking force of 6 kg, with NaHCO3 and placebo, with values significantly lower for NaHCO3 (P &amp;amp;lt; 0.001). Peak anaerobic power (Wanae, peak) and the corresponding braking force (Fmax) were also determined. Fmax was significantly increased with NaHCO3 (P &amp;amp;lt; 0.001). In conclusion, the increasing rise in [LA]A and [LA]V induced by NaHCO3 may be partly explained by a decreased rate of lactate uptake by forearm skeletal muscles. NaHCO3 did not improve Wanae, peak, but improved Fmax, thus increasing FV duration.
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