scholarly journals Sex differences in mitochondrial Ca2+ handling in mouse fast-twitch skeletal muscle in vivo

2020 ◽  
Vol 128 (2) ◽  
pp. 241-251 ◽  
Author(s):  
Daiki Watanabe ◽  
Koji Hatakeyama ◽  
Ryo Ikegami ◽  
Hiroaki Eshima ◽  
Kazuyoshi Yagishita ◽  
...  
Keyword(s):  
Skeletal Muscle ◽  
Sex Differences ◽  
Cyclopiazonic Acid ◽  
Atpase Inhibitor ◽  
Fiber Volume ◽  
Male And Female ◽  
Significant Difference ◽  
Mitochondrial Volume ◽  
Fast Twitch

We investigated sex differences in mitochondrial Ca2+ handling properties in mouse fast-twitch skeletal muscle. Changes in cytoplasmic Ca2+ concentration ([Ca2+]cyto) were measured in vivo using tibialis anterior muscles from male and female mice. The muscles were exposed to increasing concentrations of cyclopiazonic acid [CPA; sarcoplasmic reticulum (SR) Ca2+-ATPase inhibitor] (from 10 to 30 to 50 μM at 10 min intervals). Thirty minutes after treatment, [Ca2+]cyto was increased by 31.6 ± 2.0% and 13.5 ± 4.5% of initial [Ca2+]cyto in male and female muscles, respectively, and there was a significant difference between sexes. However, muscle preincubation for 5 min with 10 μM carbonyl cyanide-4-(trifluoromethoxy) phenylhydrazone (an inhibitor of mitochondria Ca2+ uptake) eradicated this difference between sexes with respect to the CPA-induced [Ca2+]cyto increase. Both intermyofibrillar mitochondrial number and volume, assessed in longitudinal fiber sections, were higher in females compared with males (mitochondria number: 13.1 ± 1.0 in males vs. 19.9 ± 2.3 in females; mitochondrial volume: 0.034 ± 0.004 μm3/μm3 fiber volume in males vs. 0.066 ± 0.008 μm3/μm3 fiber volume in females, both P < 0.05). There were no sex differences in the content of SR Ca2+-ATPase, mitochondrial Ca2+ uniporter, mitofusin (Mfn) 1, or Mfn2. These results suggest that 1) mitochondrial Ca2+ uptake ability is greater in female than male myocytes, and 2) this superior Ca2+ uptake ability of female myocytes is due, partly, to the higher intermyofibrillar mitochondrial content but not to the expression of mitochondrial proteins related to mitochondrial Ca2+ uptake. NEW & NOTEWORTHY This investigation presents evidence that female versus male fast-twitch muscle exhibits a greater mitochondrial calcium ion uptake capability that is partly conferred by the higher intermyofibrillar mitochondrial volume density.

scholarly journals Inhibiting myosin-ATPase reveals a dynamic range of mitochondrial respiratory control in skeletal muscle

2011 ◽  
Vol 437 (2) ◽  
pp. 215-222 ◽  
Author(s):  
Christopher G. R. Perry ◽  
Daniel A. Kane ◽  
Chien-Te Lin ◽  
Rachel Kozy ◽  
Brook L. Cathey ◽  
...  
Keyword(s):  
Skeletal Muscle ◽  
Dynamic Range ◽  
Energy Charge ◽  
Respiratory Control ◽  
Basic Research ◽  
Dependent Manner ◽  
Atpase Inhibitor ◽  
Wide Range ◽  
The Impact

Assessment of mitochondrial ADP-stimulated respiratory kinetics in PmFBs (permeabilized fibre bundles) is increasingly used in clinical diagnostic and basic research settings. However, estimates of the Km for ADP vary considerably (~20–300 μM) and tend to overestimate respiration at rest. Noting that PmFBs spontaneously contract during respiration experiments, we systematically determined the impact of contraction, temperature and oxygenation on ADP-stimulated respiratory kinetics. BLEB (blebbistatin), a myosin II ATPase inhibitor, blocked contraction under all conditions and yielded high Km values for ADP of >~250 and ~80 μM in red and white rat PmFBs respectively. In the absence of BLEB, PmFBs contracted and the Km for ADP decreased ~2–10-fold in a temperature-dependent manner. PmFBs were sensitive to hyperoxia (increased Km) in the absence of BLEB (contracted) at 30 °C but not 37 °C. In PmFBs from humans, contraction elicited high sensitivity to ADP (Km<100 μM), whereas blocking contraction (+BLEB) and including a phosphocreatine/creatine ratio of 2:1 to mimic the resting energetic state yielded a Km for ADP of ~1560 μM, consistent with estimates of in vivo resting respiratory rates of <1% maximum. These results demonstrate that the sensitivity of muscle to ADP varies over a wide range in relation to contractile state and cellular energy charge, providing evidence that enzymatic coupling of energy transfer within skeletal muscle becomes more efficient in the working state.

Characteristics of phosphate-induced Ca2+ efflux from the SR in mechanically skinned rat skeletal muscle fibers

2000 ◽  
Vol 278 (1) ◽  
pp. C126-C135 ◽  
Author(s):  
Adrian M. Duke ◽  
Derek S. Steele
Keyword(s):  
Skeletal Muscle ◽  
Creatine Kinase ◽  
Muscle Fibers ◽  
Cyclopiazonic Acid ◽  
Creatine Phosphate ◽  
Ruthenium Red ◽  
Rat Skeletal Muscle ◽  
Atpase Inhibitor ◽  
Skeletal Muscle Fibers ◽  
Efflux Pathway

The effects of Pi on sarcoplasmic reticulum (SR) Ca2+ regulation were studied in mechanically skinned rat skeletal muscle fibers. Brief application of caffeine was used to assess the SR Ca2+ content, and changes in concentration of Ca2+([Ca2+]) within the cytosol were detected with fura 2 fluorescence. Introduction of Pi (1–40 mM) induced a concentration-dependent Ca2+ efflux from the SR. In solutions lacking creatine phosphate (CP), the amplitude of the Pi-induced Ca2+ transient approximately doubled. A similar potentiation of Pi-induced Ca2+ release occurred after inhibition of creatine kinase (CK) with 2,4-dinitrofluorobenzene. In the presence of ruthenium red or ryanodine, caffeine-induced Ca2+ release was almost abolished, whereas Pi-induced Ca2+ release was unaffected. However, introduction of the SR Ca2+ ATPase inhibitor cyclopiazonic acid effectively abolished Pi-induced Ca2+ release. These data suggest that Pi induces Ca2+ release from the SR by reversal of the SR Ca2+ pump but not via the SR Ca2+ channel under these conditions. If this occurs in intact skeletal muscle during fatigue, activation of a Ca2+efflux pathway by Pi may contribute to the reported decrease in net Ca2+ uptake and increase in resting [Ca2+].

Activation of glycogen synthase in skeletal muscle: effects of insulin in slow- and fast-twitch muscles in vivo

1997 ◽  
Vol 25 (1) ◽  
pp. 102S-102S
Author(s):  
Lee G. D. Fryer ◽  
Mark J. Holness ◽  
Mary C. Sugden
Keyword(s):  
Skeletal Muscle ◽  
Glycogen Synthase ◽  
Fast Twitch

Skeletal muscle fiber type comparison of pyruvate dehydrogenase phosphatase activity and isoform expression in fed and food-deprived rats

2007 ◽  
Vol 292 (2) ◽  
pp. E571-E576 ◽  
Author(s):  
Paul J. LeBlanc ◽  
Robert A. Harris ◽  
Sandra J. Peters
Keyword(s):  
Skeletal Muscle ◽  
Protein Content ◽  
Food Deprivation ◽  
Pyruvate Dehydrogenase ◽  
Fiber Type ◽  
Fiber Types ◽  
Mitochondrial Volume ◽  
Coordinate Changes ◽  
Pyruvate Dehydrogenase Phosphatase ◽  
Fast Twitch

Fiber type specificity of pyruvate dehydrogenase (PDH) phosphatase (PDP) was determined in fed (CON) and 48-h food-deprived (FD) rats. PDP activity and isoform protein content were determined in soleus (slow-twitch oxidative), red gastrocnemius (RG; fast-twitch oxidative glycolytic), and white gastrocnemius (WG; fast-twitch glycolytic) muscles. When normalized for mitochondrial volume, there was no difference in PDP activity between muscle types or CON and FD. When expressed per gram wet tissue weight, PDP activity was higher in RG compared with soleus and WG in both CON and FD rats. PDP activities from CON muscles were 1.48 ± 0.19, 2.68 ± 0.65, and 1.20 ± 0.33 nmol·min−1·g wet tissue wt−1 in soleus, RG, and WG, respectively, and decreased in FD muscles (1.22 ± 0.22, 2.00 ± 0.57, and 0.84 ± 0.18 nmol·min−1·g wet tissue wt−1). This correlated with increased PDP2 protein, however, only in RG, as PDP2 was not detectable in soleus or WG. PDP1 protein was not responsive to food deprivation in all fiber types. In conclusion, PDP activity and protein content were higher in fast-twitch oxidative glycolytic muscles from CON and FD rats, identifying a unique inter- and intramuscular distribution. FD induced a small but significant decrease in PDP activity that was partially due to decreases in PDP2 protein. As a result, coordinate changes to PDP activity opposite to those of the other regulatory enzyme, PDH kinase, during food deprivation would maximize the inactivation of skeletal muscle PDH and enhance carbohydrate conservation during periods of limited carbohydrate supply.

scholarly journals Effect of glucocorticoid excess on skeletal muscle and heart protein synthesis in adult and old rats

1998 ◽  
Vol 79 (3) ◽  
pp. 297-304 ◽  
Author(s):  
Isabelle Savary ◽  
Elisabeth Debras ◽  
Dominique Dardevet ◽  
Claire Sornet ◽  
Pierre Capitan ◽  
...  
Keyword(s):  
Skeletal Muscle ◽  
Protein Synthesis ◽  
Food Intake ◽  
Tibialis Anterior ◽  
Muscle Wasting ◽  
Recovery Period ◽  
Disease States ◽  
Old Rats ◽  
Fast Twitch

This study was carried out to analyse glucocorticoid-induced muscle wasting and subsequent recovery in adult (6-8 months) and old (18-24 months) rats because the increased incidence of various disease states results in hypersecretion of glucocorticoids in ageing. Adult and old rats received dexamethasone in their drinking water for 5 or 6 d and were then allowed to recover for 3 or 7 d. As dexamethasone decreased food intake, all groups were pair-fed to dexamethasonetreated old rats (i.e. the group that had the lowest food intake). At the end of the treatment, adult and old rats showed significant increases in blood glucose and plasma insulin concentrations. This increase disappeared during the recovery period. Protein synthesis of different muscles was assessed in vivo by a flooding dose of [13C]valine injected subcutaneously 50 min before slaughter. Dexamethasone induced a significant decrease in protein synthesis in fast-twitch glycolytic and oxidative glycolytic muscles (gastrocnemius, tibialis anterior, extensor digitorum longus). The treatment affected mostly ribosomal efficiency. Adult dexamethasone-treated rats showed an increase in protein synthesis compared with their pair-fed controls during the recovery period whereas old rats did not. Dexamethasone also significantly decreased protein synthesis in the predominantly oxidative soleus muscle but only in old rats, and increased protein synthesis in the heart of adult but not of old rats. Thus, in skeletal muscle, the catabolic effect of dexamethasone is maintained or amplified during ageing whereas the anabolic effect in heart is depressed. These results are consistent with muscle atrophy occurring with ageing.

Steroid effects on permeability of rat thymic lymphocytes to α-aminoisobutyrate

1963 ◽  
Vol 205 (3) ◽  
pp. 446-452 ◽  
Author(s):  
Melvin Blecher
Keyword(s):  
Skeletal Muscle ◽  
Extracellular Fluid ◽  
In Vivo Studies ◽  
Metabolic Inhibitors ◽  
Active Process ◽  
Low Concentrations ◽  
Significant Difference ◽  
Adrenalectomized Rats

In vitro studies of the flux of α-aminoisobutyrate-1-C14 (AIB) between rat thymic lymphocytes and extracellular fluid have revealed that: a) the amino acid enters cells but is not further metabolized; b) at low concentrations, similar to those of amino acids in plasma, the net influx and efflux of AIB exhibit properties of an active process; and c) influx of AIB is inhibited, and efflux stimulated, by deoxycorticosterone (DOC), by metabolic inhibitors, and by other specific steroids. In vivo studies of the distribution of AIB between serum and tissue demonstrated that administration of DOC to adrenalectomized rats inhibited concentration of AIB by thymus, diaphragm, and skeletal muscle, augmented uptake by liver, and increased the serum level of AIB. Prior adrenalectomy of donor rats resulted in no change from normal in the in vitro capacity of thymic lymphocytes to take up AIB. There was no significant difference from normal in the in vivo concentration of AIB by thymus, liver, and skeletal muscle of adrenalectomized rats, although uptake by diaphragm was decreased compared to normal control animals.

31P NMR quantitation of phosphorus metabolites in rat heart and skeletal muscle in vivo

2001 ◽  
Vol 281 (2) ◽  
pp. H882-H887 ◽  
Author(s):  
Sam Hitchins ◽  
Julie M. Cieslar ◽  
Geoffrey P. Dobson
Keyword(s):  
Skeletal Muscle ◽  
Rat Heart ◽  
Signal Amplitude ◽  
Phosphorus Compounds ◽  
External Reference ◽  
Significant Difference ◽  
External Standard ◽  
Phosphorus Metabolites ◽  
Tissue Phosphorus

The aim of this study was to examine two methods of 31P NMR quantitation of phosphocreatine (PCr), ATP, and Pi in rat heart and skeletal muscle in vivo. The first method employed an external standard of phenylphosphonic acid (PPA; 10 mM), and the second method used an enzymatic measurement of tissue ATP equated to the area under the βATP peak. With the use of the external standard, the concentrations of ATP, PCr, and Pi in the rat heart were 4.48 ± 0.33, 9.21 ± 0.65, and 2.25 ± 0.16 μmol/g wet wt, respectively. With the use of the internal ATP standard, measured on the same tissue, the contents (means ± SE) were 4.78 ± 0.19, 9.83 ± 0.18, and 2.51 ± 0.33 μmol/g wet wt, respectively ( n = 7). In skeletal muscle, ATP, PCr, and Pi were 6.09 ± 0.19, 23.44 ± 0.88, and 1.81 ± 0.18 μmol/g wet wt using the PPA standard and 6.03 ± 0.19, 23.30 ± 1.30, and 1.82 ± 0.19 μmol/g wet wt using the internal ATP standard ( n = 6). There was no significant difference for each metabolite as measured by the two methods of quantification in heart or skeletal muscle. The results validate the use of an external reference positioned symmetrically above the coil and imply that each has similar NMR sensitivities (similar signal amplitude per mole of 31P between PPA and tissue phosphorus compounds). We conclude that PCr, ATP, and Pi are nearly 100% visible in the normoxic heart and nonworking skeletal muscle given the errors of measurement.

THE ROLE OF TESTOSTERONE AND ANDROSTENEDIONE AS PRECURSORS OF EPITESTOSTERONE IN GUINEA PIGS (IN VIVO AND IN VITRO STUDIES)

1971 ◽  
Vol 67 (1) ◽  
pp. 187-196 ◽  
Author(s):  
Marian Szamatowicz ◽  
Michel Drosdowsky ◽  
Max F. Jayle
Keyword(s):  
Sex Differences ◽  
Guinea Pigs ◽  
In Vitro Studies ◽  
Male And Female ◽  
Testosterone Production ◽  
Liver Slices

ABSTRACT After injection of [7α-3H] androstenedione and [4-14C] testosterone into male and female guinea pigs, doubly labelled aetiocholanolone, 5α-androstanedione and epiandrosterone were identified in the urine. No epitestosterone was detected. Ovaries, testes, adrenals and liver slices were incubated with the same precursors. Epitestosterone production was observed in all organs except in the adrenals. According to the epitestosterone 3H/14C ratio, it can be concluded that in guinea pigs an interconversion of testosterone, androstenedione and epitestosterone takes place. In liver, androstenedione is preferentially converted to epitestosterone without sex differences, whereas in ovary and testis epitestosterone derives preferentially from testosterone.

scholarly journals Sex Differences in Constitutive Autophagy

2014 ◽  
Vol 2014 ◽  
pp. 1-5 ◽  
Author(s):  
Sara Oliván ◽  
Ana Cristina Calvo ◽  
Raquel Manzano ◽  
Pilar Zaragoza ◽  
Rosario Osta
Keyword(s):  
Skeletal Muscle ◽  
Spinal Cord ◽  
Sex Differences ◽  
Sexual Dimorphism ◽  
Animal Models ◽  
Sex Bias ◽  
Wild Type ◽  
Male And Female ◽  
Physiological Conditions ◽  
Sequestosome 1

Sex bias has been described nowadays in biomedical research on animal models, although sexual dimorphism has been confirmed widely under pathological and physiological conditions. The main objective of our work was to study the sex differences in constitutive autophagy in spinal cord and skeletal muscle tissue from wild type mice. To examine the influence of sex on autophagy, mRNA and proteins were extracted from male and female mice tissues. The expressions of microtubule-associated protein 1 light chain 3 (LC3) and sequestosome 1 (p62), markers to monitor autophagy, were analyzed at 40, 60, 90, and 120 days of age. We found significant sex differences in the expression of LC3 and p62 in both tissues at these ages. The results indicated that sex and tissue specific differences exist in constitutive autophagy. These data underlined the need to include both sexes in the experimental groups to minimize any sex bias.

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