scholarly journals Isoform expression in the multiple soluble malate dehydrogenase of Hoplias malabaricus (Erythrinidae, Characiformes)

2003 ◽  
Vol 63 (1) ◽  
pp. 7-15 ◽  
Author(s):  
M. R. Aquino-Silva ◽  
M. L. B. Schwantes ◽  
A. R. Schwantes
Keyword(s):  
Skeletal Muscle ◽  
Malate Dehydrogenase ◽  
Tandem Duplication ◽  
Carbon Flow ◽  
Substrate Affinity ◽  
Kinetic Properties ◽  
Thermal Stabilities ◽  
Hoplias Malabaricus ◽  
Isoform Expression

Kinetic properties and thermal stabilities of Hoplias malabaricus liver and skeletal muscle unfractionated malate dehydrogenase (MDH, EC 1.1.1.37) and its isolated isoforms were analyzed to further study the possible sMDH-A* locus duplication evolved from a recent tandem duplication. Both A (A1 and A2) and B isoforms had similar optima pH (7.5-8.0). While Hoplias A isoform could not be characterized as thermostable, B could as thermolabile. A isoforms differed from B isoform in having higher Km values for oxaloacetate. The possibly duplicated A2 isoform showed higher substrate affinity than the A1. Hoplias duplicated A isoforms may influence the direction of carbon flow between glycolisis and gluconeogenesis.

Some kinetic properties of skeletal muscle pyruvate kinase from air-breathing and water-breathing fish of the Amazon

1978 ◽  
Vol 56 (4) ◽  
pp. 751-758 ◽  
Author(s):  
J. H. A. Fields ◽  
W. R. Driedzic ◽  
C. J. French ◽  
P. W. Hochachka
Keyword(s):  
Skeletal Muscle ◽  
Pyruvate Kinase ◽  
Adenosine Diphosphate ◽  
Kinetic Properties ◽  
Air Breathing ◽  
Hoplias Malabaricus ◽  
Arapaima Gigas ◽  
Saturation Kinetics ◽  
Muscle Pyruvate Kinase ◽  
Hoplerythrinus Unitaeniatus

The kinetic properties of pyruvate kinase from skeletal muscle were studied in two species of air-breathing fish, Hoplerythrinus unitaeniatus and Arapaima gigas, and two species of water-breathing fish, Hoplias malabaricus and Osteoglossum bicirrhosum. It was found that the enzymes from Hoplias and Hoplerythrinus showed hyperbolic saturation kinetics for all substrates, were activated slightly by fructose 1,6-diphosphate, and were inhibited by phosphocreatine and citrate. The enzyme from Hoplias was inhibited by alanine, whereas the enzyme from Hoplerythrinus was not. The enzymes from Arapaima and Osteoglossum showed hyperbolic saturation kinetics for adenosine diphosphate, but the saturation kinetics for phusphoenol-pyruvate were sigmoidal. These enzymes were strongly activated by fructose 1,6-diphosphate and strongly inhibited by alanine, the former completely reversing the inhibition by the latter. Phosphocreatine and citrate were also found to be inhibitors of these enzymes, but the inhibition by phosphocreatine was not reversed by additions of fructose 1,6-diphosphate. The enzymes from the water-breathing fish were more sensitive to inhibition by alanine than were those from the air-breathing fish, but in other respects the enzymes were very similar.

scholarly journals Influence of rapid changes in cytosolic pH on oxidative phosphorylation in skeletal muscle: theoretical studies

2002 ◽  
Vol 365 (1) ◽  
pp. 249-258 ◽  
Author(s):  
Bernard KORZENIEWSKI ◽  
Jerzy A. ZOLADZ
Keyword(s):  
Skeletal Muscle ◽  
Creatine Kinase ◽  
Oxidative Phosphorylation ◽  
Kinetic Properties ◽  
Main Role ◽  
Anaerobic Glycolysis ◽  
Cytosolic Ph ◽  
Intensive Exercise ◽  
Proton Production ◽  
The Stability

Cytosolic pH in skeletal muscle may vary significantly because of proton production/consumption by creatine kinase and/or proton production by anaerobic glycolysis. A computer model of oxidative phosphorylation in intact skeletal muscle developed previously was used to study the kinetic effect of these variations on the oxidative phosphorylation system. Two kinds of influence were analysed: (i) via the change in pH across the inner mitochondrial membrane and (ii) via the shift in the equilibrium of the creatine kinase-catalysed reaction. Our simulations suggest that cytosolic pH has essentially no impact on the steady-state fluxes and most metabolite concentrations. On the other hand, rapid acidification/alkalization of cytosol causes a transient decrease/increase in the respiration rate. Furthermore, changes in pH seem to affect significantly the kinetic properties of transition between resting state and active state. An increase in pH brought about by proton consumption by creatine kinase at the onset of exercise lengthens the transition time. At intensive exercise levels this pH increase could lead to loss of the stability of the system, if not compensated by glycolytic H+ production. Thus our theoretical results stress the importance of processes/mechanisms that buffer/compensate for changes in cytosolic proton concentration. In particular, we suggest that the second main role of anaerobic glycolysis, apart from additional ATP supply, may be maintaining the stability of the system at intensive exercise.

Effect of Dietary Creatine on Skeletal Muscle Myosin Heavy Chain Isoform Expression in an Animal Model of Uremia

2004 ◽  
Vol 96 (4) ◽  
pp. e103-e110 ◽  
Author(s):  
Youri E.C. Taes ◽  
Marijn Speeckaert ◽  
Evelien Bauwens ◽  
Marc R. De Buyzere ◽  
Johan Libbrecht ◽  
...  
Keyword(s):  
Skeletal Muscle ◽  
Animal Model ◽  
Myosin Heavy Chain ◽  
Heavy Chain ◽  
Skeletal Muscle Myosin ◽  
Myosin Heavy Chain Isoform ◽  
Isoform Expression ◽  
Muscle Myosin

Training-induced changes in skeletal muscle Na+-K+ pump number and isoform expression in rats with chronic heart failure

2003 ◽  
Vol 94 (6) ◽  
pp. 2225-2236 ◽  
Author(s):  
Bryan Helwig ◽  
Katherine M. Schreurs ◽  
Joslyn Hansen ◽  
K. Sue Hageman ◽  
Michael G. Zbreski ◽  
...  
Keyword(s):  
Heart Failure ◽  
Skeletal Muscle ◽  
Chronic Heart Failure ◽  
Exercise Training ◽  
Left Ventricular ◽  
Β Subunit ◽  
Severe Left Ventricular Dysfunction ◽  
Subunit Expression ◽  
Run Time ◽  
Isoform Expression

The mechanisms responsible for the decrements in exercise performance in chronic heart failure (CHF) remain poorly understood, but it has been suggested that sarcolemmal alterations could contribute to the early onset of muscular fatigue. Previously, our laboratory demonstrated that the maximal number of ouabain binding sites (Bmax) is reduced in the skeletal muscle of rats with CHF (Musch TI, Wolfram S, Hageman KS, and Pickar JG. J Appl Physiol 92: 2326–2334, 2002). These reductions may coincide with changes in the Na+-K+-ATPase isoform (α and β) expression. In the present study, we tested the hypothesis that reductions in Bmax would coincide with alterations in the α- and β-subunit expression of the sarcolemmal Na+-K+-ATPase of rats with CHF. Moreover, we tested the hypothesis that exercise training would increase Bmax along with producing significant changes in α- and β-subunit expression. Rats underwent a sham operation (sham; n = 10) or a surgically induced myocardial infarction followed by random assignment to either a control (MI; n = 16) or exercise training group (MI-T; n = 16). The MI-T rats performed exercise training (ET) for 6–8 wk. Hemodynamic indexes demonstrated that MI and MI-T rats suffered from severe left ventricular dysfunction and congestive CHF. Maximal oxygen uptake (V˙o 2 max) and endurance capacity (run time to fatigue) were reduced in MI rats compared with sham. Bmax in the soleus and plantaris muscles and the expression of the α2-isoform of the Na+-K+-ATPase in the red portion of the gastrocnemius (gastrocnemiusred) muscle were reduced in MI rats. After ET, V˙o 2 max and run time to fatigue were increased in the MI-T group of rats. This coincided with increases in soleus and plantaris Bmax and the expression of the α2-isoform in the gastrocnemiusred muscle. In addition, the expression of the β2-isoform of the gastrocnemiusred muscle was increased in the MI-T rats compared with their sedentary counterparts. This study demonstrates that CHF-induced alterations in skeletal muscle Na+-K+-ATPase, including Bmax and isoform expression, can be partially reversed by ET.

Time course adaptations in rat skeletal muscle isomyosins during compensatory growth and regression

1987 ◽  
Vol 63 (5) ◽  
pp. 2111-2121 ◽  
Author(s):  
R. W. Tsika ◽  
R. E. Herrick ◽  
K. M. Baldwin
Keyword(s):  
Skeletal Muscle ◽  
Atpase Activity ◽  
Time Course ◽  
Compensatory Growth ◽  
Myosin Isoforms ◽  
Plantaris Muscle ◽  
Slow Myosin ◽  
Protein Pool ◽  
Isoform Expression ◽  
Myofibril Protein

The purpose of this study was to ascertain the time course of change during both compensatory growth (hypertrophy) and subsequent growth regression on myosin isoform expression in rodent fast-twitch plantaris muscle in response to functional overload (induced by removal of synergists). Peak hypertrophy of the plantaris muscle (92%) occurred after 9 wk of overload. After 7 wk of overload regression (induced by a model of hindlimb unweighting), muscle weight returned to within 30% of control values. Myofibril protein content (mg/g muscle) remained relatively constant throughout the overload period but became significantly depressed relative to control values after 7 wk of regression. However, when expressed on a per muscle basis (mg/muscle) no differences existed at this time point (t = 7 wk regression). The distribution of native myosin isoforms in the myofibril protein pool of the overloaded plantaris muscle reflected a progressive increase (23% at t = 9 wk; P less than 0.001) in the relative proportion of slow myosin (Sm). This change was also accompanied by increases in intermediate myosin (Im) as well as the repression of the fast myosin one (Fm1) isoform (P less than 0.001). These shifts in Sm and Fm1 isoform expression were gradually reversed during the regression period, whereas Im remained elevated relative to control values. These adaptive changes in myosin isoform expression during both hypertrophy and regression were further supported by concomitant shifts in both myosin adenosinetriphosphatase (ATPase) activity (decreased during overload) and slow myosin light chain (SLC) expression. However, during regression the changes in myosin isoform expression and myosin ATPase were not as synchronous as they were during overload. Estimation of the mixed myosin heavy chain (MHC) half-life (t 1/2), using a linear model that assumes zero-order synthesis and first-order degradation kinetics, revealed t 1/2 values of approximately 19 and 10 days for the overload and regression periods, respectively. Collectively these data suggest that 1) skeletal muscle myosin isoforms and corresponding ATPase activity are in a dynamic state of change, although not completely synchronous, in response to altered muscle stress, and 2) the kinetics of change in the mixed MHC protein pool are slower during compensatory growth compared with regression of growth.

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