Fatigue of the mammalian diaphragm in vitro

1982 ◽  
Vol 53 (2) ◽  
pp. 440-447 ◽  
Author(s):  
S. G. Kelsen ◽  
M. L. Nochomovitz
Keyword(s):  
Duty Cycle ◽  
Phrenic Nerve ◽  
Isometric Tension ◽  
Neural Element ◽  
Sprague Dawley ◽  
Fatigue Process ◽  
Diaphragmatic Muscle ◽  
Diaphragmatic Fatigue ◽  
Diaphragm In Vitro

Diaphragm fatigue was studied in innervated diaphragm strips from 63 Sprague-Dawley rats. The experiments examined 1) the effect on the rate of diaphragmatic fatigue of increases in the diaphragm's duty cycle, i.e., the ratio of the period of diaphragmatic contraction (Ti) to the duration of a cycle of contraction and rest (Ttot) and 2) the possibility that impaired neural transmission contributed to the fatigue process. Alterations in the duty cycle of the diaphragm were simulated by varying the pattern of electrical stimuli applied cyclically to the phrenic nerve. Fatigue was assessed from the rate of fall of isometric tension when the muscle was made to contract 90 times/min. The contribution of neural element fatigue was assessed by comparing the tension during phrenic nerve stimulation to the tension developed when the muscle was stimulated directly. Increasing the duty cycle (Ti/Ttot) from 25 to 50 to 75% increased the rate of diaphragmatic fatigue progressively. Holding Ti/Ttot constant at 75%, while varying Ti and Ttot, did not affect the rate of fatigue. Increases in duty cycle appear to increase the rate of fatigue by increasing the number of times the contractile process was activated. In fatigued muscle strips diaphragmatic tension was greater in directly stimulated muscle than in muscle strips activated via the phrenic nerve. The results indicate that 1) when the breathing action of the diaphragm is simulated in vitro, increases in duty cycle accelerate the fatigue process and 2) failure of transmission of phrenic impulses to diaphragmatic muscle cells contributes to the fall in tension during fatigue.

Contractile properties of the shortening rat diaphragm in vitro

1987 ◽  
Vol 62 (3) ◽  
pp. 1111-1116 ◽  
Author(s):  
I. A. Mardini ◽  
R. J. McCarter
Keyword(s):  
Isometric Tension ◽  
Contractile Properties ◽  
Rat Diaphragm ◽  
Experimental Conditions ◽  
Diaphragmatic Fatigue ◽  
Definition Of ◽  
Diaphragm In Vitro ◽  
The Relationship ◽  
Frequency Of Stimulation

Diaphragmatic fatigue has been defined in terms of the failure of the muscle to continue to generate a given level of tension. Appropriate shortening of the diaphragm is, however, just as important for adequate ventilation. In this study we have examined in vitro the contractile properties of the rat diaphragm under afterloaded isotonic conditions and the effect of fatigue on the ability of the diaphragm to shorten. Shortening of the muscle strips was found to depend on size of afterload, frequency of stimulation, duration of stimulation, and initial length of the muscle. The afterloaded isotonic length-tension relationship coincided with the relationship between length and active isometric tension only for relatively small afterloads. Fatigue of the muscle strips, induced by isometric or afterloaded isotonic contractions, was associated with a decline in the extent of shortening as well as a decrease in active isometric tension. Ability to shorten and ability to develop isometric tension did not decrease to the same extent under all conditions. We conclude that active shortening, as well as active isometric tension, is decreased by muscular fatigue and that changes in these properties can be different depending on experimental conditions. The results suggest that the definition of diaphragmatic fatigue should be expanded to include the ability of the muscle to shorten by an appropriate amount. The results also suggest that measurement of isometric performance may not provide a complete estimate of the overall performance of the fatigued diaphragm.

Uptake and binding of thyroxine and triiodothyronine by rat diaphragm in vitro

1961 ◽  
Vol 200 (5) ◽  
pp. 1029-1031 ◽  
Author(s):  
Allen Lein ◽  
Robert M. Dowben
Keyword(s):  
Binding Capacity ◽  
Single Species ◽  
Affinity Constant ◽  
Tissue Binding ◽  
Sprague Dawley ◽  
Simple Diffusion ◽  
Sprague Dawley Rats ◽  
The Difference ◽  
Diaphragm In Vitro

Hemidiaphragms from weanling Sprague-Dawley rats were incubated in Krebs-Ringer buffer containing 1.3 x 10–7 m l-thyroxine or l-triiodothyronine labeled with radioiodine. Triiodothyronine uptake was about twice as rapid as thyroxine uptake. The data were consistent with a kinetic analysis based on a two-step process: 1) simple diffusion into the tissue (rate-limiting step) and 2) binding to cellular proteins (a process that occurs very rapidly compared to diffusion). The diffusion constants were calculated to be kd(T4) = 0.153 cm3/min and kd(T3) = 0.352 cm3/min. The data suggest a single species of tissue-binding site with identical tissue-binding capacity and binding affinity for both triiodothyronine and thyroxine. Maximum binding was found to be 28 x 10–4 µm/g tissue and the affinity constant for binding was 1.4 x 104 g/µm. The difference in the rate of accumulation of thyroxine and triiodothyronine appears to be due only to the difference in the diffusion rate. A direct rate equation for the accumulation of thyroid hormone was derived. Points calculated by means of this equation fit remarkably well with the experimental data.

scholarly journals Chemokine Receptor and Ligand Upregulation in the Diaphragm during Endotoxemia and Pseudomonas Lung Infection

2009 ◽  
Vol 2009 ◽  
pp. 1-11 ◽  
Author(s):  
Alexandre Demoule ◽  
Maziar Divangahi ◽  
Linda Yahiaoui ◽  
Gawiyou Danialou ◽  
Dusanka Gvozdic ◽  
...  
Keyword(s):  
Constitutive Expression ◽  
Dominant Negative ◽  
Free Radical Scavengers ◽  
Diaphragmatic Dysfunction ◽  
Intratracheal Administration ◽  
Diaphragmatic Muscle ◽  
Inflammatory Protein ◽  
Novel Method ◽  
Diaphragm In Vitro

Sepsis-induced diaphragmatic inflammation has been associated with respiratory failure, but the role of chemokines in this process has not been evaluated. Here we sought to study the local expression and molecular regulation of the chemokines, regulated upon activation normal T cell expressed and secreted (RANTES) and macrophage inflammatory protein (MIP)-1α, in the murine diaphragm during sepsis. Constitutive expression levels of RANTES and MIP-1α, as well as their receptors, CCR1 and CCR5, were significantly higher in diaphragm than limb muscle. Sepsis was induced by acute lipopolysaccharide (LPS) delivery or subacutely by intratracheal administration of livePseudomonas aeruginosabacteria. Both sepsis models triggered a marked upregulation of RANTES and MIP-1αin the diaphragm. In vitro, stimulation of diaphragmatic muscle cells with LPS also led to RANTES upregulation. Inhibition of the NF-kB pathway using pharmacologic or dominant negative genetic approaches blocked the LPS-induced RANTES upregulation, while free radical scavengers had no effect. We conclude that sepsis leads to greatly increased expression of RANTES, MIP-1αand their cognate receptors in the diaphragm. Manipulation of the NF-kB pathway and other regulators of chemokine expression in the diaphragm could represent a novel method for mitigating the skeletal muscle inflammatory response associated with sepsis-induced diaphragmatic dysfunction.

Preparation of cultured astrocytes for x-ray microanalysis

1989 ◽  
Vol 47 ◽  
pp. 988-989
Author(s):  
N.K.R. Smith ◽  
K.E. Hunter ◽  
P. Mobley ◽  
L.P. Felpel
Keyword(s):  
Cultured Cells ◽  
Elemental Content ◽  
Elemental Distribution ◽  
Sprague Dawley ◽  
X Ray ◽  
Cultured Astrocytes ◽  
Freeze Dried ◽  
Ultimate Objective

Electron probe energy dispersive x-ray microanalysis (XRMA) offers a powerful tool for the determination of intracellular elemental content of biological tissue. However, preparation of the tissue specimen , particularly excitable central nervous system (CNS) tissue , for XRMA is rather difficult, as dissection of a sample from the intact organism frequently results in artefacts in elemental distribution. To circumvent the problems inherent in the in vivo preparation, we turned to an in vitro preparation of astrocytes grown in tissue culture. However, preparations of in vitro samples offer a new and unique set of problems. Generally, cultured cells, growing in monolayer, must be harvested by either mechanical or enzymatic procedures, resulting in variable degrees of damage to the cells and compromised intracel1ular elemental distribution. The ultimate objective is to process and analyze unperturbed cells. With the objective of sparing others from some of the same efforts, we are reporting the considerable difficulties we have encountered in attempting to prepare astrocytes for XRMA.Tissue cultures of astrocytes from newborn C57 mice or Sprague Dawley rats were prepared and cultured by standard techniques, usually in T25 flasks, except as noted differently on Cytodex beads or on gelatin. After different preparative procedures, all samples were frozen on brass pins in liquid propane, stored in liquid nitrogen, cryosectioned (0.1 μm), freeze dried, and microanalyzed as previously reported.

An In Vitro Cytotoxicity Assay Using Rat Hepatocytes and MTT and Coomassie Blue Dye as Indicators

1991 ◽  
Vol 19 (3) ◽  
pp. 352-360
Author(s):  
Kazuhiko Otoguro ◽  
Kanki Komiyama ◽  
Satoshi Ωmura ◽  
Charles A. Tyson
Keyword(s):  
Mtt Assay ◽  
Membrane Integrity ◽  
Cell Number ◽  
Cellular Protein ◽  
Blue Dye ◽  
Tetrazolium Salt ◽  
Sprague Dawley ◽  
Lactate Dehydrogenase Activity ◽  
Coomassie Blue

Isolated hepatocytes from male Sprague-Dawley rats suspended in culture medium supplemented with either 0.2 or 2% bovine serum albumin (BSA) were allowed to attach to collagen coated 96-well dishes. Ten test chemicals from the MEIC list and salicylic acid were added individually to the dishes, and at the end of 24 and 48 hours, cytotoxicity was determined by measuring MTT (tetrazolium salt) reduction (mitochondrial integrity) and total cellular protein using Coomassie blue dye (reflecting cell number). Total cellular lactate dehydrogenase activity was also determined in some experiments, as an indicator of plasma membrane integrity. The relative toxicities of the test chemicals were quantified by the estimation of EC10, EC20 and EC50 values for each parameter. Except for one chemical, digoxin, in the MTT assay, cytotoxic potency increased with incubation time. The hepatocytes tended to be more sensitive to the chemicals in medium containing 0.2% BSA than in medium containing 2% BSA. Simple linear regression analyses of the log transformed data from the MTT assay versus log oral LD50 in rats for the test chemicals gave the best results using EC10 at 24 hours (r2 = 0.86). With protein as the cytotoxic indicator, the best results were obtained with EC values in the medium containing 2% BSA, again at 24 hours (r2 = 0.83). These results suggest that the MTT and Coomassie blue dye assays could be useful indicators for testing the cytotoxic potential of chemicals in rat hepatocyte cultures.

scholarly journals Action of Insulin on Transport of l-Alanine into Rat Diaphragm in Vitro

1973 ◽  
Vol 248 (18) ◽  
pp. 6450-6455
Author(s):  
Thomas R. Riggs ◽  
K. Janet McKirahan
Keyword(s):  
Rat Diaphragm ◽  
Diaphragm In Vitro

scholarly journals Stamina-Enhancing Effects of Human Adipose-Derived Stem Cells

2021 ◽  
Vol 30 ◽  
pp. 096368972110354
Author(s):  
Eun-Jung Yoon ◽  
Hye Rim Seong ◽  
Jangbeen Kyung ◽  
Dajeong Kim ◽  
Sangryong Park ◽  
...  
Keyword(s):  
Physical Activity ◽  
Stem Cells ◽  
Locomotor Activity ◽  
Tissue Injury ◽  
Male Rats ◽  
Adipose Derived Stem Cells ◽  
Sprague Dawley ◽  
Serum Triglycerides

Stamina-enhancing effects of human adipose derived stem cells (hADSCs) were investigated in young Sprague-Dawley rats. Ten-day-old male rats were transplanted intravenously (IV) or intracerebroventricularly (ICV) with hADSCs (1 × 106 cells/rat), and physical activity was measured by locomotor activity and rota-rod performance at post-natal day (PND) 14, 20, 30, and 40, as well as a forced swimming test at PND 41. hADSCs injection increased the moving time in locomotor activity, the latency in rota-rod performance, and the maximum swimming time. For the improvement of physical activity, ICV transplantation was superior to IV injection. In biochemical analyses, ICV transplantation of hADSCs markedly reduced serum creatine phosphokinase, lactate dehydrogenase, alanine transaminase, and muscular lipid peroxidation, the markers for muscular and hepatic injuries, despite the reduction in muscular glycogen and serum triglycerides as energy sources. Notably, hADSCs secreted brain-derived neurotrophic factor (BDNF) and nerve growth factor in vitro, and increased the level of BDNF in the brain and muscles in vivo. The results indicate that hADSCs enhance physical activity including stamina not only by attenuating tissue injury, but also by strengthening the muscles via production of BDNF.

scholarly journals miR-142 downregulation alleviates rat PTSD-like behaviors, reduces the level of inflammatory cytokine expression and apoptosis in hippocampus, and upregulates the expression of fragile X mental retardation protein

2021 ◽  
Vol 18 (1) ◽  
Author(s):  
Peng-Yin Nie ◽  
Lei Tong ◽  
Ming-Da Li ◽  
Chang-Hai Fu ◽  
Jun-Bo Peng ◽  
...  
Keyword(s):  
Fragile X ◽  
Brain Regions ◽  
Synaptic Proteins ◽  
Sprague Dawley ◽  
Post Traumatic Stress ◽  
Proinflammatory Mediators ◽  
Upstream Regulator ◽  
Trace Fear ◽  
Factor Α

Abstract Background FMRP is a selective mRNA-binding protein that regulates protein synthesis at synapses, and its loss may lead to the impairment of trace fear memory. Previously, we found that FMRP levels in the hippocampus of rats with post-traumatic stress disorder (PTSD) were decreased. However, the mechanism underlying these changes remains unclear. Methods Forty-eight male Sprague-Dawley rats were randomly divided into four groups. The experimental groups were treated with the single-prolonged stress (SPS) procedure and injected with a lentivirus-mediated inhibitor of miR-142-5p. Behavior test as well as morphology and molecular biology experiments were performed to detect the effect of miR-142 downregulation on PTSD, which was further verified by in vitro experiments. Results We found that silence of miRNA-142 (miR-142), an upstream regulator of FMRP, could alleviate PTSD-like behaviors of rats exposed to the SPS paradigm. MiR-142 silence not only decreased the levels of proinflammatory mediators, such as interleukin-1β, interleukin-6, and tumor necrosis factor-α, but also increased the expressive levels of synaptic proteins including PSD95 and synapsin I in the hippocampus, which was one of the key brain regions associated with PTSD. We further detected that miR-142 silence also downregulated the transportation of nuclear factor kappa-B (NF-κB) into the nuclei of neurons and might further affect the morphology of neurons. Conclusions The results revealed miR-142 downregulation could alleviate PTSD-like behaviors through attenuating neuroinflammation in the hippocampus of SPS rats by binding to FMRP.

scholarly journals Knockdown of long non-coding RNA LEF1-AS1 attenuates apoptosis and inflammatory injury of microglia cells following spinal cord injury

2021 ◽  
Vol 16 (1) ◽  
Author(s):  
Sheng-Yu Cui ◽  
Wei Zhang ◽  
Zhi-Ming Cui ◽  
Hong Yi ◽  
Da-Wei Xu ◽  
...  
Keyword(s):  
Spinal Cord ◽  
Spinal Cord Injury ◽  
Cell Viability ◽  
Microglial Cells ◽  
Protective Effects ◽  
Loss Of Function ◽  
Sprague Dawley ◽  
Cord Injury ◽  
Apoptosis And Inflammation

Abstract Background Spinal cord injury (SCI) is associated with health burden both at personal and societal levels. Recent assessments on the role of lncRNAs in SCI regulation have matured. Therefore, to comprehensively explore the function of lncRNA LEF1-AS1 in SCI, there is an urgent need to understand its occurrence and development. Methods Using in vitro experiments, we used lipopolysaccharide (LPS) to treat and establish the SCI model primarily on microglial cells. Gain- and loss of function assays of LEF1-AS1 and miR-222-5p were conducted. Cell viability and apoptosis of microglial cells were assessed via CCK8 assay and flow cytometry, respectively. Adult Sprague-Dawley (SD) rats were randomly divided into four groups: Control, SCI, sh-NC, and sh-LEF-AS1 groups. ELISA test was used to determine the expression of TNF-α and IL-6, whereas the protein level of apoptotic-related markers (Bcl-2, Bax, and cleaved caspase-3) was assessed using Western blot technique. Results We revealed that LncRNA LEF1-AS1 was distinctly upregulated, whereas miR-222-5p was significantly downregulated in LPS-treated SCI and microglial cells. However, LEF1-AS1 knockdown enhanced cell viability, inhibited apoptosis, as well as inflammation of LPS-mediated microglial cells. On the contrary, miR-222-5p upregulation decreased cell viability, promoted apoptosis, and inflammation of microglial cells. Mechanistically, LEF1-AS1 served as a competitive endogenous RNA (ceRNA) by sponging miR-222-5p, targeting RAMP3. RAMP3 overexpression attenuated LEF1-AS1-mediated protective effects on LPS-mediated microglial cells from apoptosis and inflammation. Conclusion In summary, these findings ascertain that knockdown of LEF1-AS1 impedes SCI progression via the miR-222-5p/RAMP3 axis.

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