scholarly journals Characterizing SERCA function in murine skeletal muscles after 35-37 days of spaceflight

2021 ◽  
Author(s):  
Jessica L. Braun ◽  
Mia S. Geromella ◽  
Sophie I. Hamstra ◽  
Holt N. Messner ◽  
Val A. Fajardo
Keyword(s):  
Protein Content ◽  
Muscle Weakness ◽  
Total Protein ◽  
Muscle Force ◽  
Fiber Type ◽  
Muscle Relaxation ◽  
Regulatory Protein ◽  
Cellular Damage ◽  
Murine Skeletal Muscle ◽  
Muscle Unloading

AbstractIt is well established that microgravity exposure causes significant muscle weakness and atrophy via muscle unloading. On Earth, muscle unloading leads to a disproportionate loss in muscle force and size with the loss in muscle force occurring at a faster rate. Though the exact mechanisms are unknown, a role for Ca2+ dysregulation has been suggested. The sarco(endo)plasmic reticulum Ca2+ ATPase (SERCA) pump actively brings cytosolic Ca2+ into the SR, eliciting muscle relaxation and maintaining low intracellular Ca2+ ([Ca2+]i). SERCA dysfunction contributes to elevations in [Ca2+]i, leading to cellular damage and thus may contribute to the muscle weakness and atrophy observed with spaceflight. Here, we investigated SERCA function, SERCA regulatory protein content (sarcolipin, phospholamban, and neuronatin), and reactive oxygen/nitrogen species (RONS) protein adduction in murine skeletal muscle after 35-37 days of spaceflight. In male and female soleus muscles, spaceflight led to drastic impairments in Ca2+ uptake despite significant increases in SERCA1a protein content. We attribute this impairment to an increase in RONS production and elevated total protein tyrosine (T) nitration and cysteine (S) nitrosylation. Contrarily, in the tibialis anterior (TA) we observed an enhancement in Ca2+ uptake, which we attribute to a shift towards a faster muscle fiber type (i.e., increased myosin heavy chain IIb and SERCA1a) without elevated total protein T-nitration and S-nitrosylation. Thus, spaceflight affects SERCA function differently between the soleus and TA. As the soleus is severely affected by spaceflight, future studies should determine whether improving SERCA function in this muscle can mitigate muscle atrophy and weakness.

scholarly journals Characterizing SERCA Function in Murine Skeletal Muscles after 35–37 Days of Spaceflight

2021 ◽  
Vol 22 (21) ◽  
pp. 11764
Author(s):  
Jessica Braun ◽  
Mia Geromella ◽  
Sophie Hamstra ◽  
Holt Messner ◽  
Val Fajardo
Keyword(s):  
Protein Content ◽  
Muscle Weakness ◽  
Total Protein ◽  
Muscle Force ◽  
Fiber Type ◽  
Muscle Relaxation ◽  
Regulatory Protein ◽  
Cellular Damage ◽  
Murine Skeletal Muscle ◽  
Muscle Unloading

It is well established that microgravity exposure causes significant muscle weakness and atrophy via muscle unloading. On Earth, muscle unloading leads to a disproportionate loss in muscle force and size with the loss in muscle force occurring at a faster rate. Although the exact mechanisms are unknown, a role for Ca2+ dysregulation has been suggested. The sarco(endo)plasmic reticulum Ca2+ ATPase (SERCA) pump actively brings cytosolic Ca2+ into the SR, eliciting muscle relaxation and maintaining low intracellular Ca2+ ([Ca2+]i). SERCA dysfunction contributes to elevations in [Ca2+]i, leading to cellular damage, and may contribute to the muscle weakness and atrophy observed with spaceflight. Here, we investigated SERCA function, SERCA regulatory protein content, and reactive oxygen/nitrogen species (RONS) protein adduction in murine skeletal muscle after 35–37 days of spaceflight. In male and female soleus muscles, spaceflight led to drastic impairments in Ca2+ uptake despite significant increases in SERCA1a protein content. We attribute this impairment to an increase in RONS production and elevated total protein tyrosine (T) nitration and cysteine (S) nitrosylation. Contrarily, in the tibialis anterior (TA), we observed an enhancement in Ca2+ uptake, which we attribute to a shift towards a faster muscle fiber type (i.e., increased myosin heavy chain IIb and SERCA1a) without elevated total protein T-nitration and S-nitrosylation. Thus, spaceflight affects SERCA function differently between the soleus and TA.

Comparative Study of Size, Total Protein, Fibrinogen and 5-HT Content of Human and Canine Platelet Density Subpopulations

1986 ◽  
Vol 56 (03) ◽  
pp. 288-292 ◽  
Author(s):  
Diego Mezzano ◽  
Eduardo Aranda ◽  
Arnaldo Foradori
Keyword(s):  
Comparative Study ◽  
Protein Content ◽  
Cell Density ◽  
Total Protein ◽  
Unit Volume ◽  
Low Density ◽  
Dense Bodies ◽  
Artifactual Changes ◽  
Platelet Release ◽  
The Difference

SummaryThe size, total protein, fibrinogen and 5-HT content were evaluated in density subpopulations of human and canine platelets fractionated in linear arabinogalactan gradients. The methodology was assessed to ascertain that platelet separation was by density and to discard artifactual changes and platelet release during the procedure. EDTA or PGEi increased the size of human PRP-platelets, but not of dog platelets. In humans, high density (HD) platelets were 1.26 times larger and contained 1.88 times more fibrinogen, 2.23 times more 5-HT and 1.37 times more protein than low density (LD) platelets; in dogs, these density cohorts did not differ in protein content, but LD platelets were 1.29 times larger and had 1.33 times more fibrinogen and 5-HT than HD platelets. These findings suggest that cell density is mostly dependent on the protein content per unit volume of platelets (and not on dense bodies). The differences in fibrinogen and 5-HT content between HD and LD cohorts in humans and dogs may be related to platelet age. The difference in volume between HD and LD platelets in dogs is of uncertain interpretation.

scholarly journals Muscle unloading-induced metabolic remodeling is associated with acute alterations in PPARδ and UCP-3 expression

2008 ◽  
Vol 34 (2) ◽  
pp. 149-161 ◽  
Author(s):  
Dawn J. Mazzatti ◽  
Melissa A. Smith ◽  
Radu C. Oita ◽  
Fei-Ling Lim ◽  
Andrew J. White ◽  
...  
Keyword(s):  
Differential Expression ◽  
Fiber Type ◽  
Uncoupling Protein ◽  
Hindlimb Suspension ◽  
Metabolic Flexibility ◽  
Peroxisome Proliferator ◽  
Compensatory Response ◽  
Mouse Muscle ◽  
Metabolic Remodeling ◽  
Muscle Unloading

A number of physiological changes follow prolonged skeletal muscle unloading as occurs in spaceflight, bed rest, and hindlimb suspension (HLS) and also in aging. These include muscle atrophy, fiber type switching, and loss of the ability to switch between lipid and glucose usage, or metabolic inflexibility. The signaling and genomic events that precede these physiological manifestations have not been investigated in detail, particularly in regard to loss of metabolic flexibility. Here we used gene arrays to determine the effects of 24-h HLS on metabolic remodeling in mouse muscle. Acute unloading resulted in differential expression of a number of transcripts in soleus and gastrocnemius muscle, including many involved in lipid and glucose metabolism. These include the peroxisome proliferator-activated receptors (PPARs). In contrast to Ppar-α and Ppar-γ, which were downregulated by acute HLS, Ppar-δ was upregulated concomitant with increased expression of its downstream target, uncoupling protein-3 ( Ucp-3). However, differential expression of Ppar-δ was both acute and transient in nature, suggesting that regulation of PPARδ may represent an adaptive, compensatory response aimed at regulating fuel utilization and maintaining metabolic flexibility.

Prediction of Human Acute Toxicity by the Hep G2/24-hour/Total Protein Assay, with Protein Measurement by the CBQCA Method

2005 ◽  
Vol 33 (3) ◽  
pp. 207-213 ◽  
Author(s):  
Paul J. Dierickx
Keyword(s):  
Protein Content ◽  
Total Protein ◽  
Total Protein Content ◽  
Human Toxicity ◽  
Hep G2 ◽  
Vitro Assay ◽  
Protein Assay ◽  
Lowry Method ◽  
Total Protein Assay

In our previously described Hep G2/24-hour/total protein assay, protein levels were measured by using the Lowry method. This assay was the best acute in vitro assay for the prediction of human toxicity within the Multicentre Evaluation of In Vitro Cytotoxicity (MEIC) study. In order to increase the MEIC data-base with a wider range of chemicals, we were interested in introducing the more practical 3-(4-carboxybenzoyl)-quinoline-2-carboxaldehyde (CBQCA) method for the quantification of the total protein content. Therefore, we investigated whether the same good results for the prediction of acute human toxicity would be obtained with the CBQCA method. The cells were treated for 24 hours, then cytotoxicity was determined by measuring the total protein content with CBQCA. The results were quantified by using the PI50c: the concentration (in mM) of test compound required to reduce the total protein content measured with the CBQCA-method by 50% as compared to the control cells. The results were compared with the PI50, the corresponding value when the Lowry method was used. A relatively low correlation was observed between PI50 and PI50c, reflecting the large and unexpected, differences when using the two protein assays. However, when comparing the log PI50c with the human toxicity, a correlation coefficient of r2 = 0.761 ( n = 44) was obtained for exactly the same series of MEIC chemicals. This value is clearly higher than that for the Lowry method ( r2 = 0.695). Compared to the Lowry method originally used, the Hep G2/24-hour/CBQCA total protein assay has the additional important advantage that it can be very easily adapted for large-scale analyses with robotic systems, including the on-line calculation of the results.

Total protein content and protein synthesis within pre-elongation stage bovine embryos

1998 ◽  
Vol 50 (2) ◽  
pp. 139-145 ◽  
Author(s):  
J.G. Thompson ◽  
A.N.M. Sherman ◽  
N.W. Allen ◽  
L.T. McGowan ◽  
H.R. Tervit
Keyword(s):  
Protein Synthesis ◽  
Protein Content ◽  
Total Protein ◽  
Total Protein Content ◽  
Bovine Embryos

scholarly journals Surface topography of hydroxyapatite affects ROS17/2.8 cells response

2002 ◽  
Vol 16 (3) ◽  
pp. 209-215 ◽  
Author(s):  
Adalberto Luiz Rosa ◽  
Márcio Mateus Beloti ◽  
Richard van Noort ◽  
Paul Vincent Hatton ◽  
Anne Jane Devlin
Keyword(s):  
Cell Proliferation ◽  
Protein Content ◽  
Surface Topography ◽  
Cell Morphology ◽  
Total Protein ◽  
Cell Attachment ◽  
Maxillofacial Surgery ◽  
Total Protein Content ◽  
Alp Activity ◽  
Powder Pressing

Hydroxyapatite (HA) has been used in orthopedic, dental, and maxillofacial surgery as a bone substitute. The aim of this investigation was to study the effect of surface topography produced by the presence of microporosity on cell response, evaluating: cell attachment, cell morphology, cell proliferation, total protein content, and alkaline phosphatase (ALP) activity. HA discs with different percentages of microporosity (< 5%, 15%, and 30%) were confected by means of the combination of uniaxial powder pressing and different sintering conditions. ROS17/2.8 cells were cultured on HA discs. For the evaluation of attachment, cells were cultured for two hours. Cell morphology was evaluated after seven days. After seven and fourteen days, cell proliferation, total protein content, and ALP activity were measured. Data were compared by means of ANOVA and Duncan’s multiple range test, when appropriate. Cell attachment (p = 0.11) and total protein content (p = 0.31) were not affected by surface topography. Proliferation after 7 and 14 days (p = 0.0007 and p = 0.003, respectively), and ALP activity (p = 0.0007) were both significantly decreased by the most irregular surface (HA30). These results suggest that initial cell events were not affected by surface topography, while surfaces with more regular topography, as those present in HA with 15% or less of microporosity, favored intermediary and final events such as cell proliferation and ALP activity.

Endotoxin administration alters the force vs. pCa relationship of skeletal muscle fibers

2000 ◽  
Vol 278 (4) ◽  
pp. R891-R896 ◽  
Author(s):  
G. Supinski ◽  
D. Nethery ◽  
T. M. Nosek ◽  
L. A. Callahan ◽  
D. Stofan ◽  
...  
Keyword(s):  
Skeletal Muscle ◽  
Muscle Force ◽  
Fiber Type ◽  
Contractile Proteins ◽  
Hill Coefficient ◽  
Control Group ◽  
Fiber Types ◽  
Endotoxin Administration ◽  
Generating Capacity ◽  
The Hill

Recent work indicates that endotoxemia elicits severe reductions in skeletal muscle force-generating capacity. The subcellular alterations responsible for these decrements have not, however, been fully characterized. One possibility is that the contractile proteins per se are altered in endotoxemia and another is that the mechanism by which these proteins are activated is affected. The purpose of the present study was to assess the effects of endotoxin administration on the contractile proteins by examining the maximum calcium-activated force (Fmax) and calcium sensitivity of single Triton-skinned fibers of diaphragm, soleus, and extensor digitorum longus (EDL) muscles taken from control and endotoxin-treated (8 mg/kg) rats. Fibers were mounted on a force transducer and sequentially activated by serial immersion in solutions of increasing Ca2+ concentration (i.e., pCa 6.0 to pCa 5.0); force vs. pCa data were fit to the Hill equation. All fibers were typed at the conclusion of studies using gel electrophoresis. Fmax, the calcium concentration required for half-maximal activation (Ca50), and the Hill coefficient were compared as a function of muscle and fiber type for the control and endotoxin-treated animals. Control group Fmax was similar for diaphragm, soleus, and EDL fibers, i.e., 112.34 ± 2.64, 111.55 ± 3.66, and 104.05 ± 4.33 kPa, respectively. Endotoxin administration reduced the average Fmax for fibers from all three muscles to 80.25 ± 2.30, 72.47 ± 2.97, and 78.32 ± 2.43 kPa, respectively ( P < 0.001 for comparison of each to control). All fiber types in diaphragm, soleus, and EDL muscles manifested similar endotoxin-related reductions in Fmax. The Ca50 and the Hill coefficient for all fiber types and all muscles were unaffected by endotoxin administration. We speculate that these alterations in the intrinsic properties of the contractile proteins represent a major mechanism by which endotoxemia reduces muscle force-generating capacity.

Glucose transporter protein content and glucose transport capacity in rat skeletal muscles

1990 ◽  
Vol 259 (4) ◽  
pp. E593-E598 ◽  
Author(s):  
E. J. Henriksen ◽  
R. E. Bourey ◽  
K. J. Rodnick ◽  
L. Koranyi ◽  
M. A. Permutt ◽  
...  
Keyword(s):  
Protein Content ◽  
Glucose Transport ◽  
Glucose Transporter ◽  
Contractile Activity ◽  
Fiber Type ◽  
Linear Regression Analysis ◽  
Type I ◽  
Fiber Types ◽  
Transport Activity ◽  
Glut 4

The relationships among fiber type, glucose transporter (GLUT-4) protein content, and glucose transport activity stimulated maximally with insulin and/or contractile activity were studied by use of the rat epitrochlearis (15% type I-20% type II2a-65% type IIb), soleus (84-16-0%), extensor digitorum longus (EDL, 3-57-40%), and flexor digitorum brevis (FDB, 7-92-1%) muscles. Insulin-stimulated 2-deoxy-D-glucose (2-DG) uptake was greatest in the soleus, followed (in order) by the FDB, EDL, and epitrochlearis. On the other hand, contractile activity induced the greatest increase in 2-DG uptake in the FDB, followed by the EDL, soleus, and epitrochlearis. The effects of insulin and contractile activity on 2-DG uptake were additive in all the muscle preparations, with the relative rates being FDB greater than soleus greater than EDL greater than epitrochlearis. Quantitation of the GLUT-4 protein content with the antiserum R820 showed the following pattern: FDB greater than soleus greater than EDL greater than epitrochlearis. Linear regression analysis showed that whereas a relatively low and nonsignificant correlation existed between GLUT-4 protein content and 2-DG uptake stimulated by insulin alone, significant correlations existed between GLUT-4 protein content and 2-DG uptake stimulated either by contractions alone (r = 0.950) or by insulin and contractions in combination (r = 0.992). These results suggest that the differences in maximally stimulated glucose transport activity among the three fiber types may be related to differences in their content of GLUT-4 protein.

Development and regression of exercise-induced cardiac hypertrophy in rats

1979 ◽  
Vol 236 (2) ◽  
pp. H268-H272 ◽  
Author(s):  
R. C. Hickson ◽  
G. T. Hammons ◽  
J. O. Holoszy
Keyword(s):  
Cytochrome C ◽  
Protein Content ◽  
Total Protein ◽  
Female Rats ◽  
Heart Weight ◽  
Total Protein Content ◽  
Mitochondrial Marker ◽  
Time Intervals ◽  
Control Value ◽  
Exercise Induced

Adult female rats were exercised by daily swimming. All the increase in heart weight induced by the exercise occurred within 14 days and averaged 30%. The half times of the increases in heart weight and total protein content were about 4.5 days, whereas that of cytochrome c, which was used as a mitochondrial marker, was 6.5 days. The total amounts of DNA and of hydroxyproline in the heart, which were used to evaluate the degree of connective tissue hyperplasia, increased only slightly (8% and 10%, respectively). Other animals were subjected to the same swimming program for 21 days. Groups of rats were killed at various time intervals after stopping exercise. Heart weight, total protein content, and total cytochrome c content decreased rapidly initially, with 60% of the total regression of hypertrophy occurring during the first week. Thereafter, heart weight fell more gradually toward the sedentary control value. The hydroxyproline content of the heart, which was increased 10%, did not decrease during the regression of the hypertrophy.

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