End points of lactate and glucose metabolism after exhausting exercise

1980 ◽  
Vol 49 (6) ◽  
pp. 1057-1069 ◽  
Author(s):  
G. A. Brooks ◽  
G. A. Gaesser
Keyword(s):  
Skeletal Muscle ◽  
Metabolic Pathways ◽  
Slow Phase ◽  
O2 Consumption ◽  
Two Dimensional ◽  
Exhausting Exercise ◽  
Lactate Removal ◽  
Kidney Liver ◽  
O2 Debt ◽  
Rapid Incorporation

To determine the extent of metabolite oxidation, rats were injected with [U-14C]lactate, -glucose, or -bicarbonate (n = 5, each) during rest or after continuous (CE) and intermittent (IE) exercises to exhaustion. Tissue analyses of resting rats, or rats killed following CE and IE and pulse injection with [14C]lactate or -glucose (n = 72, each), were used to determine the metabolic pathways of these two substrates. Oxygen consumption (VO2) declined rapidly for the first 15 min after exercise; thereafter, VO2 declined slowly and remained elevated above resting levels for 120 min. The slow phase of decline in VO2 during recovery did not coincide with lactate removal, which occurred within 15 min. Two-dimensional radiochromatograms produced from blood, kidney, liver, skeletal muscle, and heart indicated a rapid incorporation of 14C into several amino acid pools, including alanine, glutamine, glutamate, and aspartate. Four-hour postexercise recoveries (means of CE and IE) of injected [14C]lactate were lactate (0.75%), glucose (0.52%), protein (8.57%), glycogen (18.30%), CO2 (45.18%), and HCO3- (17.72%). Greater (P < 0.05) incorporation of 14C into protein and glycogen constituents after exercise, compared with rest, was demonstrated. Incorporation of [14C]lactate into glycogen represented a significant but only minor fraction of the metabolism of lactate after exhausting exercise. It is suggested that classical explanations of excess postexercise O2 consumption (i.e., "O2 debt") are too simplistic.

scholarly journals Monocarboxylate transporters, blood lactate removal after supramaximal exercise, and fatigue indexes in humans

2005 ◽  
Vol 98 (3) ◽  
pp. 804-809 ◽  
Author(s):  
C. Thomas ◽  
S. Perrey ◽  
K. Lambert ◽  
G. Hugon ◽  
D. Mornet ◽  
...  
Keyword(s):  
Skeletal Muscle ◽  
Blood Lactate ◽  
Lactate Concentration ◽  
Monocarboxylate Transporter ◽  
Slow Phase ◽  
Vastus Lateralis Muscle ◽  
Supramaximal Exercise ◽  
Western Blots ◽  
Velocity Constant ◽  
Lactate Removal

The present study investigated whether muscular monocarboxylate transporter (MCT) 1 and 4 contents are related to the blood lactate removal after supramaximal exercise, fatigue indexes measured during different supramaximal exercises, and muscle oxidative parameters in 15 humans with different training status. Lactate recovery curves were obtained after a 1-min all-out exercise. A biexponential time function was then used to determine the velocity constant of the slow phase (γ2), which denoted the blood lactate removal ability. Fatigue indexes were calculated during 1-min all-out (FIAO) and repeated 10-s (FISprint) cycling sprints. Biopsies were taken from the vastus lateralis muscle. MCT1 and MCT4 contents were quantified by Western blots, and maximal muscle oxidative capacity ( Vmax) was evaluated with pyruvate + malate and glutamate + malate as substrates. The results showed that the blood lactate removal ability (i.e., γ2) after a 1-min all-out test was significantly related to MCT1 content ( r = 0.70, P < 0.01) but not to MCT4 ( r = 0.50, P > 0.05). However, greater MCT1 and MCT4 contents were negatively related with a reduction of blood lactate concentration at the end of 1-min all-out exercise ( r = −0.56, and r = −0.61, P < 0.05, respectively). Among skeletal muscle oxidative indexes, we only found a relationship between MCT1 and glutamate + malate Vmax ( r = 0.63, P < 0.05). Furthermore, MCT1 content, but not MCT4, was inversely related to FIAO ( r = −0.54, P < 0.05) and FISprint ( r = −0.58, P < 0.05). We concluded that skeletal muscle MCT1 expression was associated with the velocity constant of net blood lactate removal after a 1-min all-out test and with the fatigue indexes. It is proposed that MCT1 expression may be important for blood lactate removal after supramaximal exercise based on the existence of lactate shuttles and, in turn, in favor of a better tolerance to muscle fatigue.

scholarly journals Drastic reduction of calsequestrin-like proteins and impaired calcium binding in dystrophic mdx muscle

2002 ◽  
Vol 92 (2) ◽  
pp. 435-445 ◽  
Author(s):  
Kevin Culligan ◽  
Niamh Banville ◽  
Paul Dowling ◽  
Kay Ohlendieck
Keyword(s):  
Skeletal Muscle ◽  
Sarcoplasmic Reticulum ◽  
Muscular Dystrophy ◽  
Calcium Binding ◽  
Functional Decline ◽  
Two Dimensional ◽  
Drastic Reduction ◽  
Dystrophic Muscle ◽  
One Dimensional ◽  
Blotting Technique

Although the reduction in dystrophin-associated glycoproteins is the primary pathophysiological consequence of the deficiency in dystrophin, little is known about the secondary abnormalities leading to x-linked muscular dystrophy. As abnormal Ca2+ handling may be involved in myonecrosis, we investigated the fate of key Ca2+ regulatory membrane proteins in dystrophic mdx skeletal muscle membranes. Whereas the expression of the ryanodine receptor, the dihydropyridine receptor, the Ca2+-ATPase, and calsequestrin was not affected, a drastic decline in calsequestrin-like proteins of 150–220 kDa was observed in dystrophic microsomes using one-dimensional immunoblotting, two-dimensional immunoblotting with isoelectric focusing, diagonal two-dimensional blotting technique, and immunoprecipitation. In analogy, overall Ca2+ binding was reduced in the sarcoplasmic reticulum of dystrophic muscle. The reduction in Ca2+ binding proteins might be directly involved in triggering impaired Ca2+ sequestration within the lumen of the sarcoplasmic reticulum. Thus disturbed sarcolemmal Ca2+ fluxes seem to influence overall Ca2+homeostasis, resulting in distinct changes in the expression profile of a subset of Ca2+ handling proteins, which might be an important factor in the progressive functional decline of dystrophic muscle fibers.

Lactate kinetics in resting and exercising forearms during moderate-intensity supine leg exercise

1993 ◽  
Vol 74 (1) ◽  
pp. 435-443 ◽  
Author(s):  
P. G. Catcheside ◽  
G. C. Scroop
Keyword(s):  
Skeletal Muscle ◽  
Blood Lactate ◽  
Lactate Production ◽  
Voluntary Contraction ◽  
Moderate Intensity ◽  
Arterial Blood ◽  
Exercise Period ◽  
Leg Exercise ◽  
Lactate Removal ◽  
Lactate Levels

Arterial blood lactate was elevated by supine leg exercise (20 min at approximately 65% maximal oxygen uptake) in five untrained male subjects, and the contribution to blood lactate removal from passive uptake vs. metabolic disposal was compared in resting and lightly exercising (15% maximal voluntary contraction static handgrip) forearm skeletal muscle. An integrated form of the Fick equation was used to predict venous lactate levels resulting solely from passive equilibration of lactate between incoming arterial blood and the forearm muscles. In the resting forearm, predicted and measured venous lactate levels were closely correlated during the exercise period (r = 0.995, P < 0.001), indicating that lactate removal could be accounted for in terms of passive uptake alone. In the lightly exercising forearm, measured venous lactate levels were higher than both the arterial and predicted venous levels, indicating net lactate production. It was concluded that most of the blood lactate generated by moderate-intensity supine leg exercise is taken up passively and not metabolized by resting skeletal muscle and that the rate of lactate disposal is unlikely to be enhanced in lightly exercising muscle.

Insulin increases thermogenesis in rat skeletal muscle following exercise

1985 ◽  
Vol 248 (1) ◽  
pp. E148-E151
Author(s):  
T. W. Balon ◽  
A. Zorzano ◽  
M. N. Goodman ◽  
N. B. Ruderman
Keyword(s):  
Skeletal Muscle ◽  
Insulin Secretion ◽  
Glycogen Synthesis ◽  
O2 Consumption ◽  
Rat Skeletal Muscle ◽  
Additional Energy ◽  
Rat Muscle ◽  
Prior Exercise ◽  
Increase Insulin Secretion ◽  
Stimulation Of

Insulin increased O2 consumption in isolated perfused rat muscle for upward of 2 h after a treadmill run. Insulin did not increase O2 consumption in nonexercised rats, nor did prior exercise increase O2 consumption in the absence of added insulin. The stimulation of glycogen synthesis by insulin was also enhanced in muscle of previously exercised rats. The additional energy required for this was not sufficient to account for the increase in O2 consumption, however. The results indicate that insulin increases thermogenesis in skeletal muscle after exercise. They also raise the possibility that in intact organisms the thermogenic effect of foods that increase insulin secretion could be increased by prior exercise.

scholarly journals Deep Proteomics of Mouse Skeletal Muscle Enables Quantitation of Protein Isoforms, Metabolic Pathways, and Transcription Factors

2015 ◽  
Vol 14 (4) ◽  
pp. 841-853 ◽  
Author(s):  
Atul S. Deshmukh ◽  
Marta Murgia ◽  
Nagarjuna Nagaraj ◽  
Jonas T. Treebak ◽  
Jürgen Cox ◽  
...  
Keyword(s):  
Skeletal Muscle ◽  
Transcription Factors ◽  
Metabolic Pathways ◽  
Protein Isoforms ◽  
Mouse Skeletal Muscle

α-AMINO-n-BUTYRIC ACID IN TRANSAMINATION

1959 ◽  
Vol 37 (4) ◽  
pp. 599-604
Author(s):  
G. Y. N. Iyer ◽  
M. Sukumaran
Keyword(s):  
Skeletal Muscle ◽  
Butyric Acid ◽  
Direct Evidence ◽  
Rat Kidney ◽  
Transaminase Activity ◽  
Transamination Reaction ◽  
Kidney Liver

The transamination reaction between α-amino-n-butyric acid and α-keto-glutarate or pyruvate or oxaloacetate in the presence of homogenates of rat kidney, liver, heart, and skeletal muscle has been studied. Direct evidence is presented for transamination with α-ketoglutarate in the presence of the first three tissues and with pyruvate in the presence of kidney and liver. Appreciable amounts of alanine are formed in the course of transamination with oxaloacetate. Of the four tissues the liver appears to be quantitatively the most important by virtue of its mass and relatively high specific transaminase activity.

Determinants of relaxation rate in skinned frog skeletal muscle fibers

1998 ◽  
Vol 274 (6) ◽  
pp. C1608-C1615 ◽  
Author(s):  
Philip A. Wahr ◽  
J. David Johnson ◽  
Jack. A. Rall
Keyword(s):  
Skeletal Muscle ◽  
Muscle Fibers ◽  
Slow Phase ◽  
Frog Skeletal Muscle ◽  
Force Of Contraction ◽  
Thin Filaments ◽  
Fast Phase ◽  
Skeletal Muscle Fibers ◽  
Kinetics Of ◽  
Overall Kinetics

The influences of sarcomere uniformity and Ca2+ concentration on the kinetics of relaxation were examined in skinned frog skeletal muscle fibers induced to relax by rapid sequestration of Ca2+ by the photolysis of the Ca2+ chelator, diazo-2, at 10°C. Compared with an intact fiber, diazo-2-induced relaxation exhibited a faster and shorter initial slow phase and a fast phase with a longer tail. Stabilization of the sarcomeres by repeated releases and restretches during force development increased the duration of the slow phase and slowed its kinetics. When force of contraction was decreased by lowering the Ca2+concentration, the overall kinetics of relaxation was accelerated, with the slow phase being the most sensitive to Ca2+ concentration. Twitchlike contractions were induced by photorelease of Ca2+ from a caged Ca2+ (DM-Nitrophen), with subsequent Ca2+ sequestration by intact sarcoplasmic reticulum or Ca2+ rebinding to caged Ca2+. These twitchlike responses exhibited relaxation kinetics that were about twofold slower than those observed in intact fibers. Results suggest that the slow phase of relaxation is influenced by the degree of sarcomere homogeneity and rate of Ca2+ dissociation from thin filaments. The fast phase of relaxation is in part determined by the level of Ca2+ activation.

Molecular analysis of intermediate filament cytoskeleton--a putative load-bearing structure

1984 ◽  
Vol 246 (4) ◽  
pp. H566-H572 ◽  
Author(s):  
M. G. Price
Keyword(s):  
Skeletal Muscle ◽  
Molecular Analysis ◽  
Intermediate Filaments ◽  
Intermediate Filament ◽  
Direct Evidence ◽  
Two Dimensional ◽  
Myocardial Cells ◽  
Intermediate Filament Proteins ◽  
Bovine Myocardium ◽  
Bearing Structure

Myocardial cells contain a cytoskeleton of intermediate filaments connecting the myofibrils. The present molecular analysis of the myocardial cytoskeleton was designed to identify the intermediate filament proteins and examine their assembly properties. The intermediate filament proteins desmin and vimentin were isolated from adult bovine myocardium by sequential extraction, urea solubilization, and chromatography on hydroxylapatite and DEAE columns. Desmin was obtained virtually pure in one peak and in a mixture of desmin and vimentin in the trailing fractions. Intermediate filaments of different morphologies polymerized in the desmin and the desmin-vimentin fractions. Isolated myocardial desmin occurs as three isozymes and isolated myocardial vimentin as two isozymes, which co-migrate on two-dimensional gels with corresponding isozymes from bovine skeletal and smooth muscle. Polypeptides of 200,000 and 220,000 daltons that fractionate with myocardial desmin and vimentin are also present in cytoskeletons of smooth and skeletal muscle. The results provide direct evidence that myocardial desmin can assemble to form intermediate filaments, suggesting that desmin is the major component of the cytoskeletal filaments in cardiomyocytes.

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