CHANGES IN THE RESTING POTENTIAL OF SKELETAL MUSCLE IN RATS WITH COLD ACCLIMATION

1966 ◽  
Vol 44 (5) ◽  
pp. 791-802 ◽  
Author(s):  
M. H. Sherebrin ◽  
A. C. Burton
Keyword(s):  
Skeletal Muscle ◽  
Electrical Properties ◽  
Cold Acclimation ◽  
White Muscle ◽  
Single Cells ◽  
Temperature Gradients ◽  
Resting Potential ◽  
The Mean ◽  
Shivering Thermogenesis ◽  
Main Factor

The resting potential of single cells in the flexor thigh muscles of rats was measured in an attempt to find a change in the electrical properties of the cell membrane with cold acclimation, in order to identify and relate metabolic changes occurring with non-shivering thermogenesis. The mean resting potential of cells in cold-acclimated rats was found to be slightly but significantly higher than in the controls. A larger temperature gradient with depth was measured in the cold-acclimated animals than in the controls. If the Q10 of resting potential with temperature is as great as 1.16, the higher potential in the cold-acclimated rats may be accounted for by this temperature difference. The resting potential was also found to vary with depth in both groups of rats. This could not be attributed to temperature gradients, and change from red to white muscle cells with depth is thought to be the main factor for the increase of potential with depth.

A METHODOLOGICAL STUDY IN MEASURING T3 AND T4 CONCENTRATION IN RED AND WHITE SKELETAL MUSCLE AND PLASMA OF EUTHYROID RATS

1979 ◽  
Vol 90 (1) ◽  
pp. 81-89 ◽  
Author(s):  
J. W. Janssen ◽  
C. van Hardeveld ◽  
A. A. H. Kassenaar
Keyword(s):  
Skeletal Muscle ◽  
White Muscle ◽  
Female Rats ◽  
Normal Female ◽  
Tissue Samples ◽  
Tissue Extracts ◽  
Red Muscle ◽  
The Mean ◽  
Ethanol Extracts ◽  
Altered Thyroid

ABSTRACT T3 and T4 concentrations were determined in plasma and red and white skeletal muscle of the rat. Because of the small tissue samples (± 300 mg), the ultra-sensitive Wick radioimmunoassay (RIA) for serum was adapted for determination in ethanol extracts. The dilution curves of the plasma and tissue extracts showed excellent parallelism with the standard curves for both T3 and T4. The mean T4 level found in female rats (n = 6) was 22.6 ± 5.2 ng/ml in plasma and did not differ significantly between red (1.85 ± 0.28 ng/g) and white (1.90 ± 0.25 ng/g) skeletal muscle. The mean T3 level in 11 normal female rats was 0.629 ± 0.098 ng/ml in the plasma and was significantly higher in the red muscle (2.07 ± 0.26 ng/g) than in the white muscle (1.65 ± 0.20 ng/g). The higher T3 levels found in the red muscle as compared with the white muscle may help to elucidate the different responsiveness of these muscle types observed in altered thyroid states.

Characterization of non-cytosolic hexokinase activity in white skeletal muscle from goldfish (Carassius auratus L.) and the effect of cold acclimation

2010 ◽  
Vol 30 (6) ◽  
pp. 413-423 ◽  
Author(s):  
Reinaldo Sousa dos Santos ◽  
Luan Pereira Diniz ◽  
Antonio Galina ◽  
Wagner Seixas da-Silva
Keyword(s):  
Skeletal Muscle ◽  
Cold Acclimation ◽  
Carassius Auratus ◽  
White Muscle ◽  
Fold Increase ◽  
Mitochondrial Fraction ◽  
Goldfish Carassius Auratus ◽  
Phosphate Donor ◽  
Kinetics Of

HK (hexokinase) is an enzyme involved in the first step in the glucose metabolism pathway, converting glucose into G6P (glucose 6-phosphate). Owing to the importance of skeletal muscle for fish swimming and acclimation processes, we used goldfish (Carassius auratus L.) white muscle in order to investigate subcellular distribution and kinetics of HK. In this study, we report that HK activity is predominantly localized in the mitochondrial fraction [NC-HK (non-cytosolic HK)] in goldfish white muscle. Studies of the kinetic parameters revealed that the Km (Michaelis–Menten constant) for glucose was 0.41±0.03 mM and that for mannose was 3-fold lower, whereas the affinity for fructose was too low to be measured. The Km for ATP was 0.88±0.05 mM, whereas no activity was observed when either GTP or ITP was used as a phosphate donor. A moderate inhibition (20–40%) was found for ADP and AMP. Similar to mammalian HK, G6P and glucose analogues were able to promote an inhibition of between 85 and 100% of activity. Here, we found that acclimation of goldfish at 5°C promoted a 2.5-fold increase in NC-HK compared with its counterpart acclimated at 25°C. However, cytosolic HK activity was not altered after thermal acclimation. In summary, our results suggest that the goldfish has a constitutive NC-HK that shows some similarities to mammalian HK-II and, curiously, may play a role in the broad metabolic changes required during the cold acclimation process.

Metabolism and electrical activity of the heart: action of 2–4-dinitrophenol and ATP

1959 ◽  
Vol 196 (2) ◽  
pp. 377-380 ◽  
Author(s):  
Walmor Carlos de Mello
Keyword(s):  
Skeletal Muscle ◽  
Electrical Activity ◽  
Potassium Concentration ◽  
Single Cells ◽  
Sinus Node ◽  
Resting Potential ◽  
Extracellular Potassium ◽  
Perfusion Fluid ◽  
Extracellular Potassium Concentration ◽  
Diastolic Depolarization

The effects of DNP on the electrical activity of single cells of the sinus node, right auricle and A-V node, were studied with microelectrodes. It was observed that this agent caused an initial tachycardia followed by a bradycardia, a decrease in the duration of the action potential, a decrease of the resting potential and a decrease in the slope of diastolic depolarization of pacemaker tissues. A complete inhibition of the electrical activity was observed in 45 minutes after the addition of DNP to the perfusion fluid. A similar result was obtained with sodium azide. A significant recovery of the electrical activity was obtained with the use of a system with DNP and ATP. A possible increase of the extracellular potassium concentration produced by DNP similar to that observed in skeletal muscle is discussed. An incomplete loss of the resting potential observed with DNP makes it probable that at least a fraction of the resting potential is independent of the energy supplied by oxidative phosphorylation.

Changes in the Adenyl Cyclase System of Skeletal Muscle of Cold-Acclimated Rats

1974 ◽  
Vol 52 (3) ◽  
pp. 176-180 ◽  
Author(s):  
Michelle Muirhead ◽  
Jean Himms-Hagen
Keyword(s):  
Skeletal Muscle ◽  
Plasma Membrane ◽  
Cold Acclimation ◽  
Metabolic Response ◽  
Adenyl Cyclase ◽  
Nonshivering Thermogenesis ◽  
Receptor System ◽  
Adenyl Cyclase System ◽  
Shivering Thermogenesis ◽  
Stimulation Of

No change could be detected in the adenyl cylase system (basal activity, noradrenaline-stimulated activity, adrenaline-stimulated activity, fluoride-stimulated activity) of skeletal muscle of cold-acclimated rats. It is concluded that the enhancement of metabolic response to noradrenaline during cold-acclimation, which occurs principally in skeletal muscle, can not be attributed to an alteration in this component of the receptor system for noradrenaline.An increase in the activity of the catecholamine-stimulated and fluoride-stimulated adenyl cyclase of skeletal muscle occurs during the 1st week of exposure to cold and has disappeared by the time the rats are fully acclimated. This increase coincides with the period of shivering thermogenesis rather than with the development of nonshivering thermogenesis; it may be related to the intense and repeated stimulation of plasma membrane associated with shivering.

Skeletal and cardiac muscle protein turnover during cold acclimation in young rats

2000 ◽  
Vol 278 (3) ◽  
pp. R705-R711 ◽  
Author(s):  
T. A. McAllister ◽  
J. R. Thompson ◽  
S. E. Samuels
Keyword(s):  
Skeletal Muscle ◽  
Protein Synthesis ◽  
Cardiac Muscle ◽  
Cold Acclimation ◽  
Protein Turnover ◽  
Muscle Protein ◽  
Muscle Protein Turnover ◽  
Protein Mass ◽  
The Absolute

The effect of long-term cold exposure on skeletal and cardiac muscle protein turnover was investigated in young growing animals. Two groups of 36 male 28-day-old rats were maintained at either 5°C (cold) or 25°C (control). Rates of protein synthesis and degradation were measured in vivo on days 5, 10, 15, and 20. Protein mass by day 20 was ∼28% lower in skeletal muscle (gastrocnemius and soleus) and ∼24% higher in heart in cold compared with control rats ( P < 0.05). In skeletal muscle, the fractional rates of protein synthesis ( k syn) and degradation ( k deg) were not significantly different between cold and control rats, although k syn was lower (approximately −26%) in cold rats on day 5; consequent to the lower protein mass, the absolute rates of protein synthesis (approximately −21%; P < 0.05) and degradation (approximately −13%; P < 0.1) were lower in cold compared with control rats. In heart, overall, k syn(approximately +12%; P < 0.1) and k deg(approximately +22%; P < 0.05) were higher in cold compared with control rats; consequently, the absolute rates of synthesis (approximately +44%) and degradation (approximately +54%) were higher in cold compared with control rats ( P < 0.05). Plasma triiodothyronine concentration was higher ( P < 0.05) in cold compared with control rats. These data indicate that long-term cold acclimation in skeletal muscle is associated with the establishment of a new homeostasis in protein turnover with decreased protein mass and normal fractional rates of protein turnover. In heart, unlike skeletal muscle, rates of protein turnover did not appear to immediately return to normal as increased rates of protein turnover were observed beyond day 5. These data also indicate that increased rates of protein turnover in skeletal muscle are unlikely to contribute to increased metabolic heat production during cold acclimation.

scholarly journals Agrometeorological models for estimating sweet cassava yield

2018 ◽  
Vol 48 (1) ◽  
pp. 43-51
Author(s):  
Victor Brunini Moreto ◽  
Lucas Eduardo de Oliveira Aparecido ◽  
Glauco de Souza Rolim ◽  
José Reinaldo da Silva Cabral de Moraes
Keyword(s):  
Great Influence ◽  
Soil Water Storage ◽  
Percentage Error ◽  
P Value ◽  
Climate Conditions ◽  
Paulo State ◽  
State Water ◽  
The Mean ◽  
Sweet Cassava ◽  
Main Factor

ABSTRACT Brazil is the fourth largest producer of cassava in the world, with climate conditions being the main factor regulating its production. This study aimed to develop agrometeorological models to estimate the sweet cassava yield for the São Paulo state, as well as to identify which climatic variables have more influence on yield. The models were built with multiple linear regression and classified by the following statistical indexes: lower mean absolute percentage error, higher adjusted determination coefficient and significance (p-value < 0.05). It was observed that the mean air temperature has a great influence on the sweet cassava yield during the whole cycle for all regions in the state. Water deficit and soil water storage were the most influential variables at the beginning and final stages. The models accuracy ranged in 3.11 %, 6.40 %, 6.77 % and 7.15 %, respectively for Registro, Mogi Mirim, Assis and Jaboticabal.

scholarly journals Electron microscopy of synthetic myosin filaments. Evidence for cross-bridge. Flexibility and copolymer formation.

1975 ◽  
Vol 67 (1) ◽  
pp. 93-104 ◽  
Author(s):  
T D Pollard
Keyword(s):  
Skeletal Muscle ◽  
Smooth Muscle ◽  
Structural Features ◽  
Length Frequency ◽  
Single Population ◽  
Skeletal Muscle Myosin ◽  
Distinctive Features ◽  
Myosin Filaments ◽  
The Mean ◽  
Muscle Myosin

Electron micrographs of negatively stained synthetic myosin filaments reveal that surface projections, believed to be the heads of the constituent myosin molecules, can exist in two configurations. Some filaments have the projections disposed close to the filament backbone. Other filaments have all of their projections widely spread, tethered to the backbone by slender threads. Filaments formed from the myosins of skeletal muscle, smooth muscle, and platelets each have distinctive features, particularly their lengths. Soluble mixtures of skeletal muscle myosin with either smooth muscle myosin or platelet myosin were dialyzed against 0.1 M KC1 at pH 7 to determine whether the simultaneous presence of two types of myosin would influence the properties of the filaments formed. In every case, a single population of filaments formed from the mixtures. The resulting filaments are thought to be copolymers of the two types of myosin, for several reasons: (a) their length-frequency distribution is unimodal and differs from that predicted for a simple mixture of two types of myosin filaments; (b) their mean length is intermediate between the mean lengths of the filaments formed separately from the two myosins in the mixture; (c) each of the filaments has structural features characteristic of both of the myosins in the mixture; and (d) their size and shape are determined by the proportion of the two myosins in the mixture.

Dantrolene Sodium: Effects on Crustacean Muscle

1974 ◽  
Vol 52 (4) ◽  
pp. 887-890 ◽  
Author(s):  
L. L. Odette ◽  
H. L. Atwood
Keyword(s):  
Skeletal Muscle ◽  
Electrical Properties ◽  
Neuromuscular Transmission ◽  
Contractile Response ◽  
Callinectes Sapidus ◽  
Muscle Membrane ◽  
Dantrolene Sodium ◽  
Muscle Contractile ◽  
Indirect Stimulation ◽  
Vertebrate Skeletal Muscle

The effect of dantrolene sodium, a muscle relaxant effective on vertebrate skeletal muscle, has been studied on the stretcher muscle of a crab (Callinectes sapidus). The drug rapidly and reversibly attenuates the muscle contractile response to direct and indirect stimulation. Neuromuscular transmission is unaffected, as are the electrical properties of the muscle membrane. It is concluded that dantrolene sodium uncouples excitation–contraction mechanisms in crustacean tonic muscle.

Increased lipoprotein lipase activity of skeletal muscle in cold-acclimated rats

1977 ◽  
Vol 55 (12) ◽  
pp. 1241-1243 ◽  
Author(s):  
N. Bégin-Heick ◽  
H. M. C. Heick
Keyword(s):  
Skeletal Muscle ◽  
Cold Acclimation ◽  
Lipoprotein Lipase ◽  
Lipase Activity ◽  
Skeletal Muscles ◽  
Lipoprotein Lipase Activity ◽  
Slow Twitch ◽  
Respiratory Movements ◽  
Parallel Fashion

The activity of lipoprotein lipase (LPL) in the heart, diaphragm, and soleus muscles was markedly increased in cold-acclimated rats and it was even greater in rats treated with oxytetracycline (OTC) while exposed to cold. Other skeletal muscles studied had low and variable activities which were not significantly increased by cold acclimation or by cold plus OTC treatment. It appears therefore that, apart from the heart and the muscles involved in respiratory movements, LPL activity is primarily associated with those muscles which contain a predominance of slow-twitch oxidative fibers, and that the enzyme in muscle, heart, and diaphragm responds to cold acclimation and cold plus OTC treatment in a parallel fashion in these tissues.

Sign in / Sign up

Export Citation Format

Share Document