Dependence of the dynamic speckle field spectral parameters on the force of isometric contraction of human skeletal muscle

2001 ◽  
Author(s):  
Sergei C. Dick ◽  
Leonid V. Tanin ◽  
Lyudmila A. Vasilevskaya ◽  
P. N. Bagrov ◽  
T. D. Lebedeva
Keyword(s):  
Skeletal Muscle ◽  
Isometric Contraction ◽  
Human Skeletal Muscle ◽  
Spectral Parameters ◽  
Speckle Field ◽  
Dynamic Speckle

No Change in Insulin Mediators in Human Skeletal Muscle During Isometric Contraction or Recovery

1996 ◽  
Vol 28 (10) ◽  
pp. 545-548 ◽  
Author(s):  
A. Katz ◽  
E. Hultma ◽  
L. Huang ◽  
C. Villar-Palasi ◽  
J. Larner
Keyword(s):  
Skeletal Muscle ◽  
Isometric Contraction ◽  
Human Skeletal Muscle

scholarly journals Contraction-mediated inactivation of glycogen synthase is accompanied by inactivation of glycogen synthase phosphatase in human skeletal muscle

1989 ◽  
Vol 259 (3) ◽  
pp. 901-904 ◽  
Author(s):  
Y Kida ◽  
A Katz ◽  
A D Lee ◽  
D M Mott
Keyword(s):  
Skeletal Muscle ◽  
Isometric Contraction ◽  
Human Skeletal Muscle ◽  
Glycogen Synthase ◽  
Active Form ◽  
Human Muscle ◽  
Maximal Voluntary Force ◽  
Before And After ◽  
Muscle Biopsies

Activities of glycogen synthase (GS) and GS phosphatase were determined on human muscle biopsies before and after isometric contraction at 2/3 maximal voluntary force. Total GS activity did not change during contraction (4.92 +/- 0.70 at rest versus 5.00 +/- 0.42 mmol/min per kg dry wt.; mean +/- S.E.M.), whereas both the active form of GS and the ratio of active form to total GS decreased by approximately 35% (P less than 0.01). GS phosphatase was inactivated in all subjects by an average of 39%, from 5.95 +/- 1.30 to 3.63 +/- 0.97 mmol/min per kg dry wt. (P less than 0.01). It is suggested that at least part of the contraction-induced inactivation of GS is due to an inactivation of GS phosphatase.

Failure of glutamate dehydrogenase system to predict oxygenation state of human skeletal muscle

1990 ◽  
Vol 259 (1) ◽  
pp. C26-C28 ◽  
Author(s):  
A. Katz ◽  
M. K. Spencer ◽  
K. Sahlin
Keyword(s):  
Skeletal Muscle ◽  
Metabolic Rate ◽  
Glutamate Dehydrogenase ◽  
Isometric Contraction ◽  
Human Skeletal Muscle ◽  
Redox State ◽  
Mitochondrial Redox State ◽  
Metabolite Ratio ◽  
Tissue Contents ◽  
Total Tissue

In a recent study, the total tissue contents of glutamate (Glu), ammonium (NH+4), and 2-oxoglutarate (2-OG) were used to estimate changes in the mitochondrial redox state ([NAD+]/[NADH]) of contracting skeletal muscle with intact circulation [Am. J. Physiol. 253 (Cell Physiol. 22): C263-C268, 1987]. These metabolites participate in the glutamate dehydrogenase (GDH) reaction, which, based on a number of assumptions, theoretically enables calculation of the mitochondrial redox state as follows (brackets indicate concentrations): [NAD+]/[NADH] = ([NH+4] [2-OG])/[( Glu]Kapp), where Kapp is the apparent equilibrium constant for GDH. The purpose of this study was to determine whether changes in the total tissue contents of Glu, NH+4, and 2-OG could be used to predict a reduction of the mitochondrial redox state in anoxic skeletal muscle. Anoxia was induced in the quadriceps femoris muscle by 10 min of circulatory occlusion (low metabolic rate) and isometric contraction to fatigue (high metabolic rate). The mean (+/- SE) value for the metabolite ratio ([NH+4][2-OG]/[Glu]) at rest was 6 +/- 3 mmol/kg dry wt (x 10(-4]. No significant change occurred after circulatory occlusion (4 +/- 2 x 10(-4); P greater than 0.05), whereas an almost 60-fold increase was observed after isometric contraction (P less than 0.05). Because the muscle was anoxic under both conditions, a significant decrease in the metabolite ratio should have occurred. These data demonstrate that changes in total tissue contents of Glu, NH+4, and 2-OG cannot be used to estimate changes in the redox and oxygenation state of mitochondria in intact human skeletal muscle.

scholarly journals Absence of phosphocreatine resynthesis in human calf muscle during ischaemic recovery

1993 ◽  
Vol 291 (3) ◽  
pp. 681-686 ◽  
Author(s):  
B Quistorff ◽  
L Johansen ◽  
K Sahlin
Keyword(s):  
Skeletal Muscle ◽  
Time Resolution ◽  
Isometric Contraction ◽  
Human Skeletal Muscle ◽  
Voluntary Contraction ◽  
Calf Muscle ◽  
Elevated Concentration ◽  
Anaerobic Glycolysis ◽  
Phosphocreatine Resynthesis ◽  
Human Calf

Changes in the metabolites phosphocreatine (PCr), Pi and ATP were quantified by 31P n.m.r. spectroscopy in the human calf muscle during isometric contraction and recovery under ischaemic conditions. Time resolution of the measurements was 10 s. During a 30-60 s ischaemic isometric contraction, PCr decreased linearly at a rate of 1.17%/s (relative to the resting value) at a contraction strength equivalent to 70% of the maximal voluntary contraction (MVC) and at a rate of 2.43%/s at 90% MVC. There was a corresponding increase in Pi but the concentration of ATP did not change. pH decreased linearly during contraction by 4.22 and 8.23 milli-pH units/s at 70 and 90% MVC respectively. During a subsequent 5 min interval of ischaemic recovery, PCr, Pi, ATP, phosphomonoesters and calculated free ADP, free AMP and pH retained the value they had attained by the end of contraction with no significant recovery. Thus it is concluded that anaerobic glycolysis and glycogenolysis is halted momentarily on termination of contraction and that PCr is not resynthesized during ischaemic recovery. This paradoxical arrest of glycolytic flow in spite of the very significantly elevated concentration of potent activators such as Pi and free AMP clearly indicates that parameters other than PCr, ATP, Pi, calculated pH, free ADP and free AMP regulate glycolysis and glycogenolysis of human skeletal muscle very efficiently under ischaemic conditions.

A method of recording from single muscle fibers or motor units in human skeletal muscle

1964 ◽  
Vol 19 (2) ◽  
pp. 366-368 ◽  
Author(s):  
Donald S. Pierce ◽  
Irving H. Wagman
Keyword(s):  
Skeletal Muscle ◽  
Motor Unit ◽  
Isometric Contraction ◽  
Human Skeletal Muscle ◽  
Motor Units ◽  
Hard Metal ◽  
Human Muscle ◽  
Single Muscle ◽  
Single Motor Unit ◽  
Tungsten Microelectrode

It is possible to record single muscle fiber and single motor unit potentials with a tungsten microelectrode inserted percutaneously (without discomfort) into human muscle. Potentials averaging 10–12 mv, 2–4 msec in duration, have been recorded from such muscles as the gastrocnemius and pectoralis major. Firing of the motor units can be followed almost to a maximum isometric contraction without the action potentials being lost in a mass of other motor unit potentials. A technique has also been developed whereby the position of a microelectrode in a human muscle during isometric contraction can be controlled by means of a micromanipulator. The possibility of inserting hard metal microelectrodes into human skeletal muscle percutaneously and positioning them with a micromanipulator substantially widens the range of the experimental work that can be carried on to elucidate the electrophysiological phenomena concerned in human skeletal muscle contraction. intramuscular tungsten microelectrode; isotonic and isometric contraction measurement Submitted on August 2, 1963

Sign in / Sign up

Export Citation Format

Share Document