scholarly journals Noninvasive Monitoring of Training Induced Muscle Adaptation with -MRS: Fibre Type Shifts Correlate with Metabolic Changes

2013 ◽  
Vol 2013 ◽  
pp. 1-10 ◽  
Author(s):  
Eike Hoff ◽  
Lars Brechtel ◽  
Patrick Strube ◽  
Paul Konstanczak ◽  
Gisela Stoltenburg-Didinger ◽  
...  
Keyword(s):  
Fibre Type ◽  
Gastrocnemius Muscle ◽  
Noninvasive Monitoring ◽  
High Energy ◽  
Metabolic Changes ◽  
Resonance Spectroscopy ◽  
High Energy Phosphates ◽  
Type Ii ◽  
Fibre Type Composition ◽  
Fast Twitch

Purpose. To evaluate training induced metabolic changes noninvasively with magnetic resonance spectroscopy (-MRS) for measuring muscle fibre type adaptation.Methods. Eleven volunteers underwent a 24-week training, consisting of speed-strength, endurance, and detraining (each 8 weeks). Prior to and following each training period, needle biopsies and -MRS of the resting gastrocnemius muscle were performed. Fibre type distribution was analyzed histologically and tested for correlation with the ratios of high energy phosphates ([PCr]/[], [PCr]/[βATP] and [PCr + ]/[βATP]). The correlation between the changes of the -MRS parameters during training and the resulting changes in fibre composition were also analysed.Results. We observed an increased type-II-fibre proportion after speed-strength and detraining. After endurance training the percentage of fast-twitch fibres was reduced. The progression of the [PCr]/[]-ratio was similar to that of the fast-twitch fibres during the training. We found a correlation between the type-II-fibre proportion and [PCr]/[] (, ) or [PCr]/[βATP] (, ); the correlations between its changes (delta) and the fibre-shift were significant as well (delta[PCr]/[] , delta[PCr]/[βATP] , ).Conclusion. Shifts in fibre type composition and high energy phosphate metabolite content covary in human gastrocnemius muscle. Therefore -MRS might be a feasible method for noninvasive monitoring of exercise-induced fibre type transformation.

Magnetic resonance spectroscopy of high-energy phosphates and lactate immediately after coronary artery bypass surgery

Perfusion ◽  
1998 ◽  
Vol 13 (5) ◽  
pp. 328-333 ◽  
Author(s):  
D NF Harris ◽  
J A Wilson ◽  
S D Taylor-Robinson ◽  
K M Taylor
Keyword(s):  
Magnetic Resonance ◽  
Magnetic Resonance Spectroscopy ◽  
Cerebral Ischaemia ◽  
Artery Bypass ◽  
High Energy ◽  
Jugular Bulb ◽  
Resonance Spectroscopy ◽  
High Energy Phosphates ◽  
Intracellular Acidosis ◽  
High Incidence

Hypothermic cardiopulmonary bypass (CPB) is associated with a high incidence of neuropsychological defects, marked cerebral swelling immediately after surgery and jugular bulb desaturation during rewarming. This suggests cerebral ischaemia may occur, but evidence is indirect. We studied four patients with 31P magnetic resonance spectroscopy (MRS) and four with 1H MRS before and immediately after coronary surgery. There was no visible lactate in 1H MR spectra. In 31P MR spectra, the ratio of phosphocreatine to adenosine triphosphate was maintained (before: 2.13 ± 0.86 vs after: 2.57 ± 1.31; mean ± 1 SD) and there was no intracellular acidosis (intracellular pH: 7.1 ± 0.04 vs 7.16 ± 0.08), while phosphocreatine/inorganic phosphate was increased immediately after the operation (2.92 ± 0.37 vs 6.39 ± 2.67, p = 0.03). This suggests rebound replacement of energy stores following recovery from temporary cerebral ischaemia during CPB: intra-operative studies would be needed to test this hypothesis further.

Muscle metabolic responses to exercise above and below the “critical power” assessed using 31P-MRS

2008 ◽  
Vol 294 (2) ◽  
pp. R585-R593 ◽  
Author(s):  
Andrew M. Jones ◽  
Daryl P. Wilkerson ◽  
Fred DiMenna ◽  
Jonathan Fulford ◽  
David C. Poole
Keyword(s):  
Critical Power ◽  
Quadriceps Muscle ◽  
High Energy ◽  
Knee Extension ◽  
Work Rate ◽  
Metabolic Responses ◽  
Time To Exhaustion ◽  
Resonance Spectroscopy ◽  
High Energy Phosphates ◽  
Constant Work Rate

We tested the hypothesis that the asymptote of the hyperbolic relationship between work rate and time to exhaustion during muscular exercise, the “critical power” (CP), represents the highest constant work rate that can be sustained without a progressive loss of homeostasis [as assessed using 31P magnetic resonance spectroscopy (MRS) measurements of muscle metabolites]. Six healthy male subjects initially completed single-leg knee-extension exercise at three to four different constant work rates to the limit of tolerance (range 3–18 min) for estimation of the CP (mean ± SD, 20 ± 2 W). Subsequently, the subjects exercised at work rates 10% below CP (<CP) for 20 min and 10% above CP (>CP) for as long as possible, while the metabolic responses in the contracting quadriceps muscle, i.e., phosphorylcreatine concentration ([PCr]), Pi concentration ([Pi]), and pH, were estimated using 31P-MRS. All subjects completed 20 min of <CP exercise without duress, whereas the limit of tolerance during >CP exercise was 14.7 ± 7.1 min. During <CP exercise, stable values for [PCr], [Pi], and pH were attained within 3 min after the onset of exercise, and there were no further significant changes in these variables (end-exercise values = 68 ± 11% of baseline [PCr], 314 ± 216% of baseline [Pi], and pH 7.01 ± 0.03). During >CP exercise, however, [PCr] continued to fall to the point of exhaustion and [Pi] and pH changed precipitously to values that are typically observed at the termination of high-intensity exhaustive exercise (end-exercise values = 26 ± 16% of baseline [PCr], 564 ± 167% of baseline [Pi], and pH 6.87 ± 0.10, all P < 0.05 vs. <CP exercise). These data support the hypothesis that the CP represents the highest constant work rate that can be sustained without a progressive depletion of muscle high-energy phosphates and a rapid accumulation of metabolites (i.e., H+ concentration and [Pi]), which have been associated with the fatigue process.

Influence of intracellular acidosis on contractile function in the working rat heart

1987 ◽  
Vol 253 (6) ◽  
pp. H1499-H1505 ◽  
Author(s):  
F. M. Jeffrey ◽  
C. R. Malloy ◽  
G. K. Radda
Keyword(s):  
Stroke Volume ◽  
Intracellular Ph ◽  
Rat Heart ◽  
Contractile Function ◽  
High Energy ◽  
Resonance Spectroscopy ◽  
High Energy Phosphates ◽  
Intracellular Acidosis ◽  
Tension Development ◽  
O2 Delivery

The decrease in myocardial contractility during ischemia, hypoxia, and extracellular acidosis has been attributed to intracellular acidosis. Previous studies of the relationship between pH and contractile state have utilized respiratory or metabolic acidosis to alter intracellular pH. We developed a model in the working perfused rat heart to study the effects of intracellular acidosis with normal external pH and optimal O2 delivery. Intracellular pH and high-energy phosphates were monitored by 31P nuclear magnetic resonance spectroscopy. Hearts were perfused to a steady state with a medium containing 10 mM NH4Cl (extracellular pH, 7.4). The subsequent washout of NH3 from the cytosol generated a slight acidosis (from intracellular pH 7.0 to 6.8) which was associated with little change in the determinants of O2 consumption (rate-pressure product) and O2 delivery (coronary flow). Acidosis induced a substantial decrease in aortic flow and stroke volume which was associated with little change in peak systolic pressure. Results were qualitatively similar at different external [Ca2+] (1.75, 2.5, 3.15 mM) and preload (12 or 21 cmH2O) but were most prominent at the lowest external [Ca2+] and left atrial pressure. In contrast to this model of isolated intracellular acidosis, hearts subject to a respiratory (extracellular plus intracellular) acidosis showed a marked reduction in pressure development. It was concluded that 1) for the same intracellular acidosis the influence on tension development was more pronounced with a combined extra- and intracellular acidosis than with an isolated intracellular acidosis, and 2) stroke volume at constant preload was impaired by intracellular acidosis even though changes in developed pressure were minimal. These observations suggest that isolated intracellular acidosis has adverse effects on diastolic compliance and/or relaxation.

scholarly journals A comparison of voluntary and electrically induced contractions by interleaved 1H- and 31P-NMRS in humans

2003 ◽  
Vol 94 (3) ◽  
pp. 1012-1024 ◽  
Author(s):  
M. Vanderthommen ◽  
S. Duteil ◽  
C. Wary ◽  
J. S. Raynaud ◽  
A. Leroy-Willig ◽  
...  
Keyword(s):  
Energy Charge ◽  
High Energy ◽  
Isometric Contractions ◽  
High Energy Phosphates ◽  
Type Ii ◽  
Metabolic Pattern ◽  
Cell Recruitment ◽  
Temporal And Spatial ◽  
Voluntary Contractions ◽  
Type Ii Fibers

Skeletal muscle voluntary contractions (VC) and electrical stimulations (ES) were compared in eight healthy men. High-energy phosphates and myoglobin oxygenation were simultaneously monitored in the quadriceps by interleaved1H- and 31P-NMR spectroscopy. For the VC protocol, subjects performed five or six bouts of 5 min with a workload increment of 10% of maximal voluntary torque (MVT) at each step. The ES protocol consisted of a 13-min exercise with a load corresponding to 10% MVT. For both protocols, exercise consisted of 6-s isometric contractions and 6-s rest cycles. For an identical mechanical level (10% MVT), ES induced larger changes than VC in the Pi-to-phosphocreatine ratio [1.38 ± 1.14 (ES) vs. 0.13 ± 0.04 (VC)], pH [6.69 ± 0.11 (ES) vs. 7.04 ± 0.07 (VC)] and myoglobin desaturation [43 ± 15.9 (ES) vs. 6.1 ± 4.6% (VC)]. ES activated the muscle facing the NMR coil to a greater extent than did VCs when evaluated under identical technical conditions. This metabolic pattern can be interpreted in terms of specific temporal and spatial muscle cell recruitment. Furthermore, at identical levels of energy charge, the muscle was more acidotic and cytoplasm appeared more oxygenated during ES than during VC. These results are in accordance with a preferential recruitment of type II fibers and a relative muscle hyperperfusion during ES.

scholarly journals Tirilazad Pretreatment Improves Early Cerebral Metabolic and Blood Flow Recovery from Hyperglycemic Ischemia

1995 ◽  
Vol 15 (1) ◽  
pp. 88-96 ◽  
Author(s):  
Yuichi Maruki ◽  
Raymond C. Koehler ◽  
Jeffrey R. Kirsch ◽  
Kathleen K. Blizzard ◽  
Richard J. Traystman
Keyword(s):  
Lipid Peroxidation ◽  
Blood Flow ◽  
Intracranial Pressure ◽  
Intracellular Ph ◽  
High Energy ◽  
Vehicle Group ◽  
Resonance Spectroscopy ◽  
High Energy Phosphates ◽  
Early Reperfusion ◽  
Tirilazad Mesylate

Acidosis may augment cerebral ischemic injury by promoting lipid peroxidation. We tested the hypothesis that when acidosis is augmented by hyperglycemia, pretreatment with the 21-aminosteroid tirilazad mesylate (U74006F), a potent inhibitor of lipid peroxidation in vitro, improves early cerebral metabolic recovery. In a randomized, blinded study, anesthetized dogs received either tirilazad mesylate (1 mg/kg plus 0.2 mg/kg/h; n = 8) or vehicle (n = 8). Hyperglycemia (400–500 mg/dl) was produced prior to 30 min of global incomplete cerebral ischemia. Intracellular pH and high energy phosphates were measured by phosphorus magnetic resonance spectroscopy. During ischemia, microsphere-determined CBF decreased to 8 ± 4 ml min−1 100 g−1 and intracellular pH decreased to 5.6 ± 0.2 in both groups. During the first 20 min of reperfusion, ATP partially recovered in the vehicle group to 57 ± 21% of baseline, but then declined progressively in association with elevated intracranial pressure. By 30 min, ATP recovery was greater in the tirilazad group (77 ± 35 vs. 36 ± 19%), although postischemic hyperemia was similar. By 45 min, the tirilazad group had a higher intracellular pH (6.5 ± 0.5 vs. 5.9 ± 0.6) and a lower intracranial pressure (18 ± 6 vs. 52 ± 24 mm Hg). By 180 min, blood flow and ATP were undetectable in seven of eight vehicle-treated dogs, whereas ATP was >67% and pH was >6.7 in six of eight tirilazad-treated dogs. Thus, tirilazad acts during early reperfusion to prevent secondary metabolic decay associated with severe acidotic ischemia. If tirilazad acts by inhibiting lipid peroxidation, then these data are consistent with extreme acidosis limiting recovery by a mechanism involving lipid peroxidation.

Regional blood flow and skeletal muscle energy status in endotoxemic rats

1987 ◽  
Vol 252 (5) ◽  
pp. E581-E587 ◽  
Author(s):  
M. M. Jepson ◽  
M. Cox ◽  
P. C. Bates ◽  
N. J. Rothwell ◽  
M. J. Stock ◽  
...  
Keyword(s):  
Blood Flow ◽  
Protein Synthesis ◽  
Regional Blood Flow ◽  
High Energy ◽  
Whole Body ◽  
Sublethal Dose ◽  
Resonance Spectroscopy ◽  
High Energy Phosphates ◽  
Energy Status ◽  
Brown Adipose

Endotoxins induce muscle wasting in part as a result of depressed protein synthesis. To investigate whether these changes reflect impaired energy transduction, blood flow, O2 extraction, and high-energy phosphates in muscle and whole-body O2 consumption (VO2) have been measured. VO2 was measured for 6h after an initial sublethal dose of endotoxin (Escherichia coli lipopolysaccharide 0.3 mg/100 g body wt sc) or saline and during 6h after a second dose 24 h later. In fed or fasted rats, VO2 was either increased or better maintained after endotoxin. In anesthetized fed rats 3-4 after the second dose of endotoxin VO2 was increased, and this was accompanied by increased blood flow to liver (hepatic arterial supply), kidney, and perirenal brown adipose tissue and a 57 and 64% decrease in flow to back and hindlimb muscle, respectively, with no change in any other organ. Hindlimb arteriovenous O2 was unchanged, indicating markedly decreased aerobic metabolism in muscle, and the contribution of the hindlimb to whole-body VO2 decreased by 46%. Adenosine 5'-triphosphate levels in muscle were unchanged in endotoxin-treated rats, and this was confirmed by topical nuclear magnetic resonance spectroscopy, which also showed muscle pH to be unchanged. These results show that although there is decreased blood flow and aerobic oxidation in muscle, adenosine 5'-triphosphate availability does not appear to be compromised so that the endotoxin-induced muscle catabolism and decreased protein synthesis must reflex some other mechanism.

Muscle ATP turnover rate during isometric contraction in humans

1986 ◽  
Vol 60 (6) ◽  
pp. 1839-1842 ◽  
Author(s):  
A. Katz ◽  
K. Sahlin ◽  
J. Henriksson
Keyword(s):  
Isometric Contraction ◽  
Turnover Rate ◽  
Knee Extensor ◽  
High Energy ◽  
High Energy Phosphates ◽  
Atp Turnover ◽  
Contraction Duration ◽  
Extensor Muscles ◽  
Before And After ◽  
Fast Twitch

ATP turnover and glycolytic rates during isometric contraction in humans have been investigated. Subjects contracted the knee extensor muscles at two-thirds maximal voluntary force to fatigue (mean +/- SE, 53 +/- 4 s). Biopsies were obtained before and after exercise and analyzed for high-energy phosphates and glycogenolytic-glycolytic intermediates. Total ATP turnover was 190 +/- 7 mmol/kg dry muscle, whereas the average turnover rate was 3.7 +/- 0.2 mmol . kg dry muscle-1 . S-1. The average ATP turnover rate was positively correlated with the percentage of fast-twitch fibers in the postexercise biopsy (r = 0.71; P less than 0.05) and negatively correlated with contraction duration to fatigue (r = -0.88; P less than 0.05). At fatigue, phosphocreatine ranged from 1 to 11 mmol/kg dry muscle (86–99% depletion of value at rest), whereas lactate ranged from 59 to 101. The mean glycolytic rate was 0.83 +/- 0.05 mmol . kg dry muscle-1 . S-1 and was positively correlated with the rate of glucose 6-phosphate accumulation (r = 0.83; P less than 0.05). It is concluded that a major determinant of the ATP turnover rate is the muscle fiber composition, which is probably explained by a higher turnover rate in fast-twitch fibers; fatigue is more closely related to a low phosphocreatine content than to a high lactate content; and the increase in prephosphofructokinase intermediates is important for stimulating glycolysis during contraction.

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