Contraction parameters, myosin composition and metabolic enzymes of the skeletal muscles of the etruscan shrew Suncus etruscus and of the common European white-toothed shrew Crocidura russula (Insectivora: soricidae)

1999 ◽  
Vol 202 (18) ◽  
pp. 2461-2473 ◽  
Author(s):  
T. Peters ◽  
H.P. Kubis ◽  
P. Wetzel ◽  
S. Sender ◽  
G. Asmussen ◽  
...  
Keyword(s):  
Sarcoplasmic Reticulum ◽  
Skeletal Muscles ◽  
Time Course ◽  
Citrate Synthase ◽  
Volume Fraction ◽  
Mammalian Species ◽  
Metabolic Enzymes ◽  
Diaphragm Muscle ◽  
Crocidura Russula ◽  
Contraction Times

In the Etruscan shrew, the isometric twitch contraction times of extensor digitorum longus (EDL) and soleus muscles are shorter than in any other mammal, allowing these muscles to contract at outstandingly high contraction frequencies. This species has the highest mass-specific metabolic rate of all mammals and requires fast skeletal muscles not only for locomotion but also for effective heat production and for an extremely high ventilation rate. No differences could be detected in the fibre type pattern, the myosin heavy and light chain composition, or in the activity of the metabolic enzymes lactate dehydrogenase and citrate synthase of the two limb muscles, the EDL and the soleus, which in larger mammalian species exhibit distinct differences in contractile proteins and metabolic enzymes. All properties determined in EDL and soleus muscles of Suncus etruscus, as well as in the larger Crocidura russula, are typical for fast-oxidative fibres, and the same holds for several other skeletal muscles including the diaphragm muscle of S. etruscus. Nevertheless, the EDL and soleus muscles showed different mechanical properties in the two shrew species. Relaxation times and, in C. russula, time to peak force are shorter in the EDL than in the soleus muscle. This is in accordance with the time course of the Ca(2+) transients in these muscles. Such a result could be due to different parvalbumin concentrations, to a different volume fraction of the sarcoplasmic reticulum in the two muscles or to different Ca(2+)-ATPase activities. Alternatively, the lower content of cytosolic creatine kinase (CK) in the soleus compared with the EDL muscle could indicate that the observed difference in contraction times between these shrew muscles is due to the CK-controlled activity of their sarcoplasmic reticulum Ca(2+)-ATPase.

scholarly journals Differential distribution of ryanodine receptor type 3 (RyR3) gene product in mammalian skeletal muscles

1996 ◽  
Vol 316 (1) ◽  
pp. 19-23 ◽  
Author(s):  
Antonio CONTI ◽  
L. GORZA ◽  
Vincenzo SORRENTINO
Keyword(s):  
Skeletal Muscle ◽  
Muscle Contraction ◽  
Gene Product ◽  
Skeletal Muscles ◽  
Mammalian Species ◽  
Diaphragm Muscle ◽  
Muscle Fibres ◽  
Abdominal Muscles ◽  
Mammalian Skeletal Muscle ◽  
Specific Subset

Activation of intracellular Ca2+-release channels/ryanodine receptors (RyRs) is a fundamental step in the regulation of muscle contraction. In mammalian skeletal muscle, Ca2+-release channels containing the type 1 isoform of RyR (RyR1) open to release Ca2+ from the sarcoplasmic reticulum (SR) upon stimulation by the voltage-activated dihydropyridine receptor on the T-tubule/plasma membrane. In addition to RyR1, low levels of the mRNA of the RyR3 isoform have been recently detected in mammalian skeletal muscles. Here we report data on the distribution of the RyR3 gene product in mammalian skeletal muscles. Western-blot analysis of SR of individual muscles indicated that, at variance with the even distribution of the RyR1 isoform, the RyR3 content varies among different muscles, with relatively higher amounts being detected in diaphragm and soleus, and lower levels in abdominal muscles and tibialis anterior. In these muscles RyR3 was localized in the terminal cisternae of the SR. No detectable levels of RyR3 were observed in the extensor digitorum longus. Preferential high content of RyR3 in the diaphragm muscle was observed in several mammalian species. In situ hybridization analysis demonstrated that RyR3 transcripts are not restricted to a specific subset of skeletal-muscle fibres. Differential utilization of the RyR3 isoform in skeletal muscle may be relevant to the modulation of Ca2+ release with respect to specific muscle-contraction properties.

Etruscan shrew muscle: the consequences of being small

2002 ◽  
Vol 205 (15) ◽  
pp. 2161-2166 ◽  
Author(s):  
Klaus D. Jürgens
Keyword(s):  
Skeletal Muscles ◽  
Citrate Synthase ◽  
Small Diameter ◽  
High Energy ◽  
High Rate ◽  
Type I ◽  
Shortening Velocity ◽  
Lactate Dehydrogenase Activity ◽  
Contraction Times ◽  
Isometric Twitch

SUMMARYThe skeletal muscles of the smallest mammal, the Etruscan shrew Suncus etruscus, are functionally and structurally adapted to the requirements of an enormously high energy turnover. Isometric twitch contractions of the extensor digitorum longus (EDL) and soleus muscles are shorter than in any other mammal, allowing these muscles to contract at outstandingly high frequencies. The skeletal muscles of S. etruscus contract at up to 900 min-1 for respiration, up to 780 min-1 for running and up to 3500 min-1 for shivering. All skeletal muscles investigated lack slow-twitch type I fibres and consist only of fast-twitch type IID fibres. These fibres are optimally equipped with properties enabling a high rate of almost purely oxidative metabolism: they have a small diameter,their citrate synthase activity is higher and their lactate dehydrogenase activity is lower than in the muscles of any other mammal and they have a rapid shortening velocity. Differences in isometric twitch contraction times between different muscles are, at least in part, probably due to differences in cytosolic creatine kinase activities.

Relaxation of the diaphragm muscle: influence of ryanodine and fatigue

1988 ◽  
Vol 65 (5) ◽  
pp. 1950-1956 ◽  
Author(s):  
P. Herve ◽  
Y. Lecarpentier ◽  
F. Brenot ◽  
M. Clergue ◽  
D. Chemla ◽  
...  
Keyword(s):  
Sarcoplasmic Reticulum ◽  
Time Course ◽  
Maximum Velocity ◽  
Diaphragm Muscle ◽  
Ventricular Muscle ◽  
Active Tension ◽  
Rat Diaphragm ◽  
Adult Rat ◽  
Relaxation Maximum ◽  
Isometric Twitch

Relaxation of rat diaphragm was shown to be sensitive to load, as previously described for adult mammalian ventricular muscle, because the time course of isotonic relaxation could be changed by changing the load: the lighter the load, the greater the shortening, the quicker the relaxation. Maximum velocity of isotonic relaxation was linearly related to the extent of shortening (r = 0.90). To quantify the degree of load sensitivity, we measured the tRi, i.e., the ratio of time at which the isometric relaxation of the twitch afterloaded at 50% of the isometric peak active tension began to time at which the isometric twitch was relaxed to 50% of the isometric peak active twitch tension. tRi was 0.76 +/- 0.03 (SE) in control conditions but significantly increased to 0.91 +/- 0.02 after ryanodine, which is an inhibitor of the sarcoplasmic reticulum (SR) function, and to 0.89 +/- 0.03 after fatigue. These results suggest that in adult rat diaphragm, as in cardiac muscle, the load sensitivity of relaxation requires a well-functioning SR and that the relaxation abnormalities observed in fatigued diaphragm are related to a dysfunction of the SR.

scholarly journals Rat uterine microbiochemistry: metabolic enzyme activities stimulated by 17-beta-estradiol are localized in epithelial cells.

1987 ◽  
Vol 35 (6) ◽  
pp. 657-662 ◽  
Author(s):  
J P Holt ◽  
E Rhe
Keyword(s):  
Enzyme Activity ◽  
Smooth Muscle ◽  
Epithelial Cells ◽  
Dose Response ◽  
Enzyme Activities ◽  
Time Course ◽  
Citrate Synthase ◽  
Ovariectomized Rats ◽  
Similar Response ◽  
Estradiol Treatment

Lactate dehydrogenase (LDH; EC 1.1.1.27), citrate synthase (CS; EC 4.1.3.7), and beta-hydroxyacyl-CoA-dehydrogenase (beta-OH-acyl-CoA-DH; EC 1.1.1.35) activities were determined in each of the three major cell types of rat uterus, i.e., epithelial, stromal, and smooth muscle, using quantitative microanalytical techniques. Adult ovariectomized rats were treated with 17-beta-estradiol to determine the time course and dose response (0.025-50 micrograms/300-g rat) effect of estrogen on enzyme activity of each type of uterine cell. The use of "oil well" and enzyme-cycling microtechniques to determine the time course and the dose responses of enzyme activity changes required microassays involving 1595 microdissected single cell specimens. Estradiol treatment increased epithelial LDH, CS and beta-OH-acyl-CoA-DH activity but had no effect on these enzymes in the stroma or in smooth muscle cells. The estradiol-stimulated peak enzyme activities on Day 4 in the intervention group are compared with those in the ovariectomized rat controls as follows: LDH, 44.5 +/- 3.5 vs 22.3 +/- 3.9; CS, 3.5 +/- 0.2 vs 1.5 +/- 0.6; beta-OH-acyl-CoA-H, 3.5 +/- 0.32 vs 2.2 +/- 0.2 (mean +/- standard deviation; mol/kg/hr). Stromal cell activities (LDH, 7.4 +/- 1.0; CS, 1.2 +/- 0.2; beta-OH-acyl-CoA-DH, 0.9 +/- 0.1) were significantly lower than epithelial cell levels and were similar to smooth muscle levels. Therefore, even in the ovariectomized animal epithelial cells have markedly higher metabolic activity compared with adjacent cells. The enzyme activities are expressed as moles of substrate reacting per kilogram of dry weight per hour. All three enzymes exhibited a 17-beta-estradiol-induced dose response between 0.025-0.15 micrograms/300-g rat. The three enzymes studied all had similar response patterns to estrogen. The effect of estradiol was restricted to epithelial cells, with enzyme activities increasing to maximal levels after approximately 96 hr of hormone treatment. This study therefore not only confirms the specific and differential metabolic responses of uterine cells to estradiol treatment, but clearly demonstrates that marked metabolic differences exist between epithelial cells and stromal or smooth muscle uterine cells.

Load-matched acute and chronic exercise induce changes in mitochondrial biogenesis and metabolic markers

2021 ◽  
Author(s):  
Natalia Almeida Rodrigues ◽  
Claudio Alexandre Gobatto ◽  
Lucas Dantas Maia Forte ◽  
Filipe Antônio de Barros Sousa ◽  
Adriana Souza Torsoni ◽  
...  
Keyword(s):  
Aerobic Capacity ◽  
Skeletal Muscles ◽  
Acute Exercise ◽  
Citrate Synthase ◽  
Liver Glycogen ◽  
Chronic Exercise ◽  
Total Load ◽  
Metabolic Markers ◽  
Target Proteins ◽  
Glycogen Stores

We investigated the effects of the acute and chronic exercise, prescribed in different intensity zones, but with total load-matched on mitochondrial markers (COX-IV, Tfam, and citrate synthase (CS) activity in skeletal muscles, heart, and liver), glycogen stores, aerobic capacity and anaerobic index in swimming rats. For this, two experimental designs were performed (acute and chronic efforts). Load-matched exercises were prescribed below and above and on the anaerobic threshold (AnT), determined by the Lactate Minimum test. In chronic programs, two training prescription strategies were assessed (monotonous and linear periodized model). Results show changes in glycogen stores but no modification in the COX-IV and Tfam contents after acute exercises. In the chronic protocols, COX-IV and Tfam proteins and CS adaptations were intensity and tissue dependents. Monotonous training promoted better adaptations than the periodized model. Training at 80% of the AnT improved both performance variables, emphasizing the anaerobic index, concomitant to CS and COX-IV improvement (soleus muscle). The aerobic capacity and CS activity (gastrocnemius) were increased after 120% AnT training. In conclusion, acute exercise protocol did not promote responses in mitochondrial target proteins. An intensity and tissue dependence are reported in the chronic protocols, highlighting training at 80 and 120% of the AnT. Novelty: • Load-matched acute exercise did not enhance COX-IV and Tfam contents in skeletal muscles, heart, and liver. • In chronic exercise, COX-IV, Tfam, and citrate synthase activity adaptations were intensity and tissue dependents. •Monotonous training was more efficient than the periodized linear model in adaptations of target proteins and enzymatic activity.

Induction of a fast-oxidative phenotype by chronic muscle stimulation: histochemical and metabolic studies

1996 ◽  
Vol 270 (1) ◽  
pp. C313-C320 ◽  
Author(s):  
C. N. Mayne ◽  
H. Sutherland ◽  
J. C. Jarvis ◽  
S. J. Gilroy ◽  
A. J. Craven ◽  
...  
Keyword(s):  
Time Course ◽  
Citrate Synthase ◽  
Fiber Type ◽  
Adult Rabbit ◽  
Myosin Isoforms ◽  
Two Phase ◽  
Coa Transferase ◽  
Oxidative Phenotype ◽  
Aggregate Amount

Chronic electrical stimulation of skeletal muscle at 10 Hz induces fast-to-slow fiber type transformation. Does a lower aggregate amount of activity lead to a less complete transformation, or does it produce the same transformation over a longer time course? We examined this question by subjecting adult rabbit tibialis anterior and extensor digitorum longus muscles to continuous stimulation at 2.5 Hz for 2-12 wk. Most of the fibers acquired the histochemical and immunocytochemical characteristics of type 2A, not type 1, fibers. There was a corresponding rise in oxidative activity, but this was accompanied by a marked decline in anaerobic glycolysis. The activities of hexokinase and 3-oxoacid CoA-transferase stopped increasing after 2 wk, glutamate oxaloacetate transaminase after 4 wk, and beta-hydroxyacyl-CoA dehydrogenase after 6 wk of stimulation. Succinate dehydrogenase, citrate synthase, lactate dehydrogenase, and creatine phosphokinase continued to change up to 12 wk of stimulation. Changes in enzyme activity were not as rapid or as marked as those observed for stimulation at 10 Hz, and none showed the typical two-phase response of oxidative enzyme activities to stimulation at 10 Hz. The latter may therefore be dependent on induction of type 1 myosin isoforms.

scholarly journals Role of Mammalian Auditory Cortex in the Perception of Elementary Sound Properties

2001 ◽  
Vol 85 (6) ◽  
pp. 2350-2358 ◽  
Author(s):  
Sanjiv K. Talwar ◽  
Pawel G. Musial ◽  
George L. Gerstein
Keyword(s):  
Auditory Cortex ◽  
Time Course ◽  
Auditory Evoked Potentials ◽  
Mammalian Species ◽  
Sound Intensity ◽  
Primary Auditory Cortex ◽  
Normal Hearing ◽  
Auditory Task ◽  
Experimental Conditions

Studies in several mammalian species have demonstrated that bilateral ablations of the auditory cortex have little effect on simple sound intensity and frequency-based behaviors. In the rat, for example, early experiments have shown that auditory ablations result in virtually no effect on the rat's ability to either detect tones or discriminate frequencies. Such lesion experiments, however, typically examine an animal's performance some time after recovery from ablation surgery. As such, they demonstrate that the cortex is not essential for simple auditory behaviors in the long run. Our study further explores the role of cortex in basic auditory perception by examining whether the cortex is normally involved in these behaviors. In these experiments we reversibly inactivated the rat primary auditory cortex (AI) using the GABA agonist muscimol, while the animals performed a simple auditory task. At the same time we monitored the rat's auditory activity by recording auditory evoked potentials (AEP) from the cortical surface. In contrast to lesion studies, the rapid time course of these experimental conditions preclude reorganization of the auditory system that might otherwise compensate for the loss of cortical processing. Soon after bilateral muscimol application to their AI region, our rats exhibited an acute and profound inability to detect tones. After a few hours this state was followed by a gradual recovery of normal hearing, first of tone detection and, much later, of the ability to discriminate frequencies. Surface muscimol application, at the same time, drastically altered the normal rat AEP. Some of the normal AEP components vanished nearly instantaneously to unveil an underlying waveform, whose size was related to the severity of accompanying behavioral deficits. These results strongly suggest that the cortex is directly involved in basic acoustic processing. Along with observations from accompanying multiunit experiments that related the AEP to AI neuronal activity, our results suggest that a critical amount of activity in the auditory cortex is necessary for normal hearing. It is likely that the involvement of the cortex in simple auditory perceptions has hitherto not been clearly understood because of underlying recovery processes that, in the long-term, safeguard fundamental auditory abilities after cortical injury.

Metabolic responses to head-down suspension in hypophysectomized rats

1993 ◽  
Vol 75 (6) ◽  
pp. 2718-2726 ◽  
Author(s):  
C. R. Woodman ◽  
C. M. Tipton ◽  
J. Evans ◽  
J. K. Linderman ◽  
K. Gosselink ◽  
...  
Keyword(s):  
Muscle Mass ◽  
Time Course ◽  
Citrate Synthase ◽  
O2 Consumption ◽  
Hindlimb Muscles ◽  
Impaired Ability ◽  
Norepinephrine Concentration ◽  
Hindlimb Muscle ◽  
Before And After ◽  
Hypophysectomized Rats

Rats exposed to head-down suspension (HDS) exhibit reductions in maximal O2 consumption (VO2max) and atrophy of select hindlimb muscles. This study tested the hypothesis that an endocrine-deficient rat exposed to HDS would not exhibit reductions in VO2max or hindlimb muscle mass. Hypophysectomized (HYPX) and sham-operated (SHAM) rats were tested for VO2max before and after 28 days of HDS or cage control (CC) conditions. No significant reductions in VO2max were observed in HYPX rats. In contrast, SHAM-HDS rats exhibited a significant reduction in absolute (-16%) and relative (-29%) measures of aerobic capacity. Time course experiments revealed a reduction in VO2max in SHAM-HDS rats within 7 days, suggesting that cardiovascular adjustments to HDS occurred in the 1st wk. HDS was associated with atrophy of the soleus (-42%) in SHAM rats, whereas HYPX rats exhibited atrophy of the soleus (-36%) and plantaris (-13%). SHAM-HDS rats had significantly lower (-38%) soleus citrate synthase activities per gram muscle mass than SHAM-CC, but no significant differences existed between HYPX-HDS and -CC rats. HDS rats had an impaired ability to thermoregulate, as indicated by significantly greater temperature increases per unit run time, compared with their CC counterparts. Pretreatment plasma epinephrine levels were significantly lower in HYPX than in SHAM rats. Norepinephrine concentration was similar for all groups except HYPX-HDS, in which it was significantly higher. HDS had no significant effect on thyroxine or triiodothyronine. SHAM-HDS rats had significantly lower concentrations of testosterone and growth hormone.(ABSTRACT TRUNCATED AT 250 WORDS)

Sign in / Sign up

Export Citation Format

Share Document