Age-related differences in diaphragm muscle injury after lengthening activations

1994 ◽  
Vol 77 (5) ◽  
pp. 2125-2133 ◽  
Author(s):  
J. F. Watchko ◽  
B. D. Johnson ◽  
L. E. Gosselin ◽  
Y. S. Prakash ◽  
G. C. Sieck
Keyword(s):  
Muscle Injury ◽  
Diaphragm Muscle ◽  
Acute Injury ◽  
Stimulation Protocol ◽  
Optimal Length ◽  
Adult Rat ◽  
Age Related ◽  
Stimulus Train ◽  
Two Phases

The susceptibility of postnatal day 15 and adult rat diaphragms (DIAs) to acute injury after repetitive isovelocity lengthening activations was examined in vitro. Forces were measured during two phases of each stimulation protocol: 1) isometric phase: during the first 300 ms of each 500-ms train, DIA length was not changed; and 2) isovelocity lengthening phase: during the remaining 200 ms of each stimulus train, DIA was lengthened at a constant velocity from 90 to 110% of optimal length. At maximal activation (75 Hz and a lengthening velocity of 1.0 optimal length per second), the maximum force measured during the isometric phase and that measured during the isovelocity lengthening phase were both greater in adult DIAs than in day 15 DIAs but both declined to a greater extent in adults with repetitive activation. Ultrastructural analysis showed that after lengthening activations muscle fiber injury was very evident in adult but much less prevalent in day 15 DIAs. This difference in susceptibility between the adult and day 15 DIAs did not depend on differences in peak force or absolute velocity of lengthening. We conclude that lengthening activations result in DIA injury and that the adult is more susceptible than its younger counterpart.

scholarly journals Power fatigue of the rat diaphragm muscle

2000 ◽  
Vol 89 (6) ◽  
pp. 2215-2219 ◽  
Author(s):  
Bill T. Ameredes ◽  
Wen-Zhi Zhan ◽  
Y. S. Prakash ◽  
Rene Vandenboom ◽  
Gary C. Sieck
Keyword(s):  
Diaphragm Muscle ◽  
Fiber Types ◽  
Rat Diaphragm ◽  
Shortening Velocity ◽  
Reduction In Force ◽  
Novel Technique ◽  
Velocity Relationship ◽  
Stimulus Train ◽  
Force Velocity

We hypothesized that decrements in maximum power output (W˙max) of the rat diaphragm (Dia) muscle with repetitive activation are due to a disproportionate reduction in force (force fatigue) compared with a slowing of shortening velocity (velocity fatigue). Segments of midcostal Dia muscle were mounted in vitro (26°C) and stimulated directly at 75 Hz in 400-ms-duration trains repeated each second (duty cycle = 0.4) for 120 s. A novel technique was used to monitor instantaneous reductions in maximum specific force (Po) andW˙max during fatigue. During each stimulus train, activation was isometric for the initial 360 ms during which Po was measured; the muscle was then allowed to shorten at a constant velocity (30% V max) for the final 40 ms, and W˙max was determined. Compared with initial values, after 120 s of repetitive activation, Po andW˙max decreased by 75 and 73%, respectively. Maximum shortening velocity was measured in two ways: by extrapolation of the force-velocity relationship ( V max) and using the slack test [maximum unloaded shortening velocity ( V o)]. After 120 s of repetitive activation, V max slowed by 44%, whereas V o slowed by 22%. Thus the decrease inW˙max with repetitive activation was dominated by force fatigue, with velocity fatigue playing a secondary role. On the basis of a greater slowing of V max vs. V o, we also conclude that force and power fatigue cannot be attributed simply to the total inactivation of the most fatigable fiber types.

Changes in diaphragm muscle collagen gene expression after acute unilateral denervation

1995 ◽  
Vol 79 (4) ◽  
pp. 1249-1254 ◽  
Author(s):  
L. E. Gosselin ◽  
G. C. Sieck ◽  
R. A. Aleff ◽  
D. A. Martinez ◽  
A. C. Vailas
Keyword(s):  
Mrna Level ◽  
Diaphragm Muscle ◽  
Passive Force ◽  
Cross Link ◽  
Optimal Length ◽  
Collagen Concentration ◽  
Fischer 344 ◽  
Length Relationship ◽  
Relationship Of

The purpose of the present study was to examine the effects of acute (3 days) unilateral diaphragm denervation (DNV) on 1) levels of alpha 1(I) and alpha 1(III) procollagen mRNA; 2) collagen concentration [hydroxyproline (HYP)]; 3) amount of the nonreducible collagen cross-link hydroxylysylpyridinoline (HP); and 4) the passive force-length relationship of the muscle. The levels of alpha 1(I) and alpha 1(III) procollagen mRNA, HYP concentration, and amount of HP were measured in muscle segments from the midcostal region of DNV and intact (INT) hemidiaphragms of adult male Fischer 344 rats (250–300 g). The in vitro passive force-length relationship of DNV and INT hemidiaphragm was determined by lengthening and shortening the diaphragm muscle segments from 85 to 115% of optimal length at a constant velocity (0.6 optimal length/s). Three days after DNV, the level of alpha 1(I) procollagen mRNA was increased over 15-fold in the DNV hemidiaphragm compared with INT (P < 0.05), whereas the level of alpha 1(III) procollagen mRNA was increased by approximately sixfold in the DNV hemidiaphragm compared with INT (P < 0.05). Collagen (HYP) concentration did not differ between groups, averaging 8.7 and 8.9 micrograms/mg dry wt for the DNV and INT hemidiaphragms, respectively. In addition, there was no difference in the amount of the mature nonreducible collagen cross-link HP between the DNV and INT hemidiaphragms (0.66 vs. 0.76 mole HP/mole collagen, respectively). The amount of passive force developed during lengthening did not differ between DNV and INT hemidiaphragms. These data indicate that acute DNV of the hemidiaphragm is associated with an increase in the mRNA level of the two principal fibrillar collagen phenotypes in skeletal muscle. However, despite extensive muscle remodeling, the passive force-length relationship of the DNV hemidiaphragm is unaffected compared with the INT muscle.

scholarly journals Guide Cells Support Muscle Regeneration and Affect Neuro-Muscular Junction Organization

2021 ◽  
Vol 22 (4) ◽  
pp. 1939
Author(s):  
Flavio L. Ronzoni ◽  
Nefele Giarratana ◽  
Stefania Crippa ◽  
Mattia Quattrocelli ◽  
Marco Cassano ◽  
...  
Keyword(s):  
Muscle Regeneration ◽  
Muscle Injury ◽  
De Novo ◽  
Neuromuscular Junctions ◽  
Myogenic Differentiation ◽  
Cell Types ◽  
Acute Injury ◽  
Complex Biological Process ◽  
Junction Formation

Muscular regeneration is a complex biological process that occurs during acute injury and chronic degeneration, implicating several cell types. One of the earliest events of muscle regeneration is the inflammatory response, followed by the activation and differentiation of muscle progenitor cells. However, the process of novel neuromuscular junction formation during muscle regeneration is still largely unexplored. Here, we identify by single-cell RNA sequencing and isolate a subset of vessel-associated cells able to improve myogenic differentiation. We termed them ‘guide’ cells because of their remarkable ability to improve myogenesis without fusing with the newly formed fibers. In vitro, these cells showed a marked mobility and ability to contact the forming myotubes. We found that these cells are characterized by CD44 and CD34 surface markers and the expression of Ng2 and Ncam2. In addition, in a murine model of acute muscle injury and regeneration, injection of guide cells correlated with increased numbers of newly formed neuromuscular junctions. Thus, we propose that guide cells modulate de novo generation of neuromuscular junctions in regenerating myofibers. Further studies are necessary to investigate the origin of those cells and the extent to which they are required for terminal specification of regenerating myofibers.

ATP-sensitive K+ channel blocker glibenclamide and diaphragm fatigue during normoxia and hypoxia

1998 ◽  
Vol 85 (2) ◽  
pp. 601-608 ◽  
Author(s):  
Erik Van Lunteren ◽  
Michelle Moyer ◽  
Augusto Torres
Keyword(s):  
Relaxation Time ◽  
Diaphragm Muscle ◽  
K Channel ◽  
Adult Rat ◽  
Fatigue Development ◽  
Stimulation Paradigm ◽  
Contractile Performance ◽  
Modest Effect

The role of ATP-sensitive K+ channels in skeletal muscle contractile performance is controversial: blockers of these channels have been found to not alter, accelerate, or attenuate fatigue. The present study reexamined whether glibenclamide affects contractile performance during repetitive contraction. Experiments systematically assessed the effects of stimulation paradigm, temperature, and presence of hypoxia and in addition compared intertrain with intratrain fatigue. Adult rat diaphragm muscle strips were studied in vitro. At 37°C and normoxia, glibenclamide did not significantly affect any measure of fatigue during continuous 5- or 100-Hz or intermittent 20-Hz stimulation but progressively prolonged relaxation time during 20-Hz stimulation. At 20°C and normoxia, neither force nor relaxation rate was affected significantly by glibenclamide during 20-Hz stimulation. At 37°C and hypoxia, glibenclamide did not significantly affect fatigue at 5-Hz or intertrain fatigue during 20-Hz stimulation but reduced intratrain fatigue and prolonged relaxation time during 20-Hz stimulation. These findings indicate that, although ATP-sensitive K+ channels may be activated during repetitive contraction, their activation has only a modest effect on the rate of fatigue development.

scholarly journals Functional impact of diaphragm muscle sarcopenia in both male and female mice

2015 ◽  
Vol 309 (1) ◽  
pp. L46-L52 ◽  
Author(s):  
Sarah M. Greising ◽  
Carlos B. Mantilla ◽  
Juan S. Medina-Martínez ◽  
Jessica M. Stowe ◽  
Gary C. Sieck
Keyword(s):  
Functional Limitations ◽  
Diaphragm Muscle ◽  
Specific Force ◽  
Transdiaphragmatic Pressure ◽  
Male And Female ◽  
Female Mice ◽  
Motor Behaviors ◽  
Age Related

To perform a range of ventilatory and nonventilatory behaviors, the diaphragm muscle (DIAm) must be able to generate sufficient forces throughout the lifespan. We hypothesized that sarcopenia impacts DIAm force generation and thus limits performance of expulsive, higher force, nonventilatory behaviors. Male and female mice ( n = 79) at 6 and 24 mo of age (100 vs. 70–75% survival, respectively) were used to examine transdiaphragmatic pressure (Pdi) generation across motor behaviors in vivo and in vitro DIAm specific force. We found a significant effect of age on maximum Pdi (20–41% decline during tracheal occlusion and bilateral phrenic nerve stimulation), maximum DIAm specific force (30% decline), and DIAm fatigue resistance (15% increase). There were no differences between sexes in these age effects on DIAm performance. These results support our hypothesis that sarcopenia primarily impacts higher force, nonventilatory motor behaviors of the DIAm. Such functional limitations may have negative implications in the ability of the DIAm to generate forces needed for airway clearance in old age and thereby contribute to age-related respiratory complications.

Immunoenzymatic demonstration of the simultaneous presence of transferrin, hemopexin and albumin in a same hepatocyte and their ultrastructural localization

1978 ◽  
Vol 36 (2) ◽  
pp. 88-89
Author(s):  
M. Kraemer ◽  
J. Foucrier ◽  
J. Vassy ◽  
M.T. Chalumeau
Keyword(s):  
Plasma Proteins ◽  
Rat Hepatocytes ◽  
Ultrastructural Localization ◽  
Carrier Proteins ◽  
Normal Cells ◽  
Adult Rat ◽  
Adult Rat Hepatocytes ◽  
Monospecific Antisera ◽  
Different Levels

Some authors using immunofluorescent techniques had already suggested that some hepatocytes are able to synthetize several plasma proteins. In vitro studies on normal cells or on cells issued of murine hepatomas raise the same conclusion. These works could be indications of an hepatocyte functionnal non-specialization, meanwhile the authors never give direct topographic proofs suitable with this hypothesis.The use of immunoenzymatic techniques after obtention of monospecific antisera had seemed to us useful to bring forward a better knowledge of this problem. We have studied three carrier proteins (transferrin = Tf, hemopexin = Hx, albumin = Alb) operating at different levels in iron metabolism by demonstrating and localizing the adult rat hepatocytes involved in their synthesis.Immunological, histological and ultrastructural methods have been described in a previous work.

Aggregation of Cat Platelets in Vitro

1970 ◽  
Vol 23 (03) ◽  
pp. 601-620 ◽  
Author(s):  
Th. B Tschopp
Keyword(s):  
Adenosine Monophosphate ◽  
Blood Collection ◽  
Base Line ◽  
Reversible Aggregation ◽  
Low Concentrations ◽  
Irreversible Aggregation ◽  
High Concentrations ◽  
Two Phases ◽  
Improved Technique

SummaryAggregation of cat platelets in the citrated plasma is examined by means of Born’s absorptiometer. A marked tendency of the platelets of this species to spontaneous aggregation necessitated first of all the development of an improved technique of blood collection.A hypothesis according to which 5-HT is released from the platelets, explains the absence of oscillations on the base line of the absorptiometer, the absence of platelet swelling, when ADP is added, and the effect of stirring on the aggregation curves in cat PRP. The average volume of cat platelets amounts to 10.46 μ3 when directly fixed in the blood, when fixed from PRP to 12.17 μ3, when fixed from stirred PRP to 13.51 μ3.In low concentrations (0.3-2 μM) ADP produce reversible aggregation; in narrowly restricted, individually dissimilar mean concentrations irreversible aggregation in two phases and in high concentrations, irreversible aggregation in one phase. Like ADP serotonin produces 2 phase irreversible aggregation in concentrations of 3-10 μM, but unlike ADP, the aggregation velocity decreases again with high 5-HT concentrations (>100 μM). Adrenaline does not produce aggregation and it is likely that adenosine and adenosine monophosphate inhibit the aggregation by serotonin but not by ADP. Species differences in the aggregation of human, rabbit and cat platelets are discussed.

Age-Related Changes in the Effects of Serum from Lean and Obese Pigs on Myogenic Cell Proliferation in Vitro

1982 ◽  
Vol 54 (4) ◽  
pp. 763-768 ◽  
Author(s):  
Ronald E. Allen ◽  
Gail Robinson ◽  
Matthew J. Parsons ◽  
Robert A. Merkel ◽  
William T. Magee
Keyword(s):  
Cell Proliferation ◽  
Myogenic Cell ◽  
Age Related ◽  
Proliferation In Vitro ◽  
Age Related Changes

A Pro-Somathropic Formulation with GHR Agonistic and Pro-Thyrogenic Features (Preprint)

2019 ◽  
Author(s):  
Erdal Can Alkoclar
Keyword(s):  
Mrna Expression ◽  
Efficient Method ◽  
Age Related

BACKGROUND A Formulation consisting of 2 Dioscin and 2 Glucopyranoside Derivatives with Simultaneous GHRH Stimulative and T3 mRNA Expression Enhancimg Features. OBJECTIVE Anti Aging METHODS GH/T3 Optimization RESULTS Approved in Vitro CONCLUSIONS Endogenous GH and T3 Optimization is the an efficient method for combating age related Senility and Fatigue Symptoms

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