Spontaneous in vitro contractile activity of specimens from the abomasal wall of healthy cows and comparison among dairy breeds

2002 ◽  
Vol 63 (12) ◽  
pp. 1687-1694 ◽  
Author(s):  
Marc Zulauf ◽  
Cecile Spring ◽  
Richard Eicher ◽  
Mireille Meylan ◽  
Gaby Hirsbrunner ◽  
...  
Keyword(s):  
Contractile Activity

scholarly journals Genetic deletion of trkB.T1 increases neuromuscular function

2012 ◽  
Vol 302 (1) ◽  
pp. C141-C153 ◽  
Author(s):  
Susan G. Dorsey ◽  
Richard M. Lovering ◽  
Cynthia L. Renn ◽  
Carmen C. Leitch ◽  
Xinyue Liu ◽  
...  
Keyword(s):  
Calcium Release ◽  
Contractile Activity ◽  
Muscle Tension ◽  
Neuromuscular Synapse ◽  
Neuromuscular Function ◽  
In Vitro Assays ◽  
Tyrosine Kinase Receptor ◽  
Akt Activation

Neurotrophin-dependent activation of the tyrosine kinase receptor trkB.FL modulates neuromuscular synapse maintenance and function; however, it is unclear what role the alternative splice variant, truncated trkB ( trkB.T1), may have in the peripheral neuromuscular axis. We examined this question in trkB.T1 null mice and demonstrate that in vivo neuromuscular performance and nerve-evoked muscle tension are significantly increased. In vitro assays indicated that the gain-in-function in trkB.T1 −/− animals resulted specifically from an increased muscle contractility, and increased electrically evoked calcium release. In the trkB.T1 null muscle, we identified an increase in Akt activation in resting muscle as well as a significant increase in trkB.FL and Akt activation in response to contractile activity. On the basis of these findings, we conclude that the trkB signaling pathway might represent a novel target for intervention across diseases characterized by deficits in neuromuscular function.

Effects of ischemia and myogenic activity on active and passive mechanical properties of rat cerebral arteries

2002 ◽  
Vol 283 (6) ◽  
pp. H2268-H2275 ◽  
Author(s):  
Rebecca J. Coulson ◽  
Naomi C. Chesler ◽  
Lisa Vitullo ◽  
Marilyn J. Cipolla
Keyword(s):  
Contractile Activity ◽  
Cerebral Arteries ◽  
Biomechanical Properties ◽  
Short Term ◽  
Mechanical Stiffness ◽  
Middle Cerebral Arteries ◽  
Male Wistar Rats ◽  
Myogenic Activity ◽  
Activity Dependent

Passive (papaverine induced) and active (spontaneous pressure induced) biomechanical properties of ischemic and nonischemic rat middle cerebral arteries (MCAs) were studied under pressurized conditions in vitro. Ischemic (1 h of occlusion), contralateral, and sham-operated control MCAs were isolated from male Wistar rats ( n = 22) and pressurized using an arteriograph system that allowed control of transmural pressure (TMP) and measurement of lumen diameter and wall thickness. Three mechanical stiffness parameters were computed: overall passive stiffness (β), pressure-dependent modulus changes ( E inc,p), and smooth muscle cell (SMC) activity-dependent changes ( E inc,a). The β-value for ischemic vessels was increased compared with sham vessels (13.9 ± 1.7 vs. 9.1 ± 1.4, P < 0.05), indicating possible short-term remodeling due to ischemia. E inc,p increased with pressure in the passive vessels ( P < 0.05) but remained relatively constant in the active vessels for all vessel types, indicating that pressure-induced SMC contractile activity (i.e., myogenic reactivity) in cerebral arteries leads to the maintenance of a constant elastic modulus within the autoregulatory pressure range. E inc,a increased with pressure for all conditions, signifying that changes in stiffness are influenced by SMC activity and vascular tone.

Smooth muscle mechanical responses in vitro to bethanechol after progesterone in male rat.

1978 ◽  
Vol 235 (4) ◽  
pp. E422 ◽  
Author(s):  
L A Bruce ◽  
F M Behsudi ◽  
I E Danhof
Keyword(s):  
Smooth Muscle ◽  
Contractile Activity ◽  
Circular Muscle ◽  
Male Rat ◽  
Equal Weight ◽  
Muscarinic Agonist ◽  
Sprague Dawley ◽  
Response Curves ◽  
Dose Levels

Male Sprague-Dawley rats were pretreated subcutaneously with either progesterone (3 mg/kg per day) in a vehicle or a vehicle only for 3 days. Antral and gastroduodenal junctional tissues (GJT) were excised from both groups of animals and prepared for in vitro mechanical measurements. Responses from the circular muscle axis of these tissues were recorded with strain gauge transducers over a 30-min period. Chemical stimulation of the tissue was achieved with a muscarinic agonist, bethanechol chloride. Log-dose response curves suggested that untreated antral tissue generated stronger contractile activity than untreated GJT on an equal weight basis at bethanechol dose levels of 6.4 X 10(-6) M to 1 X 10(-4) M (P less than 0.005). Antral tissue and GJT contractile activity from the progesterone pretreated animals was significantly reduced (P less than 0.01) compared to the corresponding tissues from untreated animals at bethanechol dose levels of 6.4 X 10(-6) M and 1.28 X 10(-5) M. Progesterone pretreatment appeared to have little effect on the contractile frequency of either tissue. These results suggest possible progesteronic influences on contractile force in gastrointestinal smooth muscle.

Muscularis mucosae contraction evokes colonic secretion via prostaglandin synthesis and nerve stimulation

2003 ◽  
Vol 284 (2) ◽  
pp. G213-G220 ◽  
Author(s):  
W. H. Percy ◽  
T. H. Fromm ◽  
C. E. Wangsness
Keyword(s):  
Contractile Activity ◽  
In Vitro Study ◽  
Simultaneous Recording ◽  
Prostaglandin Synthesis ◽  
Potential Difference ◽  
Muscularis Mucosae ◽  
Mucosal Secretion ◽  
Colonic Secretion ◽  
Mucosal Innervation

This in vitro study tested the hypothesis that muscularis mucosae contractile activity contributes to rabbit colonic mucosal function by mechanisms other than simple mechanical deformation of the epithelium. Experiments were performed by using a technique that allows simultaneous recording of muscle activity and transmucosal potential difference, a measure of epithelial ion transport. ATP, bradykinin, histamine, PGE2, PGF1α, and PGF2α elicited muscularis mucosae contractions that were resistant to atropine and TTX. Only ATP-induced contractions were indomethacin sensitive, and only those to dimethylphenylpiperazinium iodide (DMPP) were reduced by atropine. All agonist-evoked increases in transmucosal potential difference were atropine resistant, and, with the exception of those to PGE2, PGF2α, and VIP, they were also TTX sensitive. Mucosal responses to ATP, bradykinin, and histamine were indomethacin sensitive, whereas those to DMPP, the prostaglandins, and VIP were not. When cyclooxygenase activity or the mucosal innervation was compromised, even maximal muscularis mucosae contractions did not produce large secretory responses. It is concluded that contraction-related prostaglandin synthesis and noncholinergic secretomotor neuron stimulation represent the physiological transduction mechanism through which muscularis mucosae motor activity is translated into mucosal secretion.

scholarly journals Contractile activity is required for the expression of neonatal myosin heavy chain in embryonic chick pectoral muscle cultures.

1986 ◽  
Vol 103 (6) ◽  
pp. 2153-2161 ◽  
Author(s):  
L C Cerny ◽  
E Bandman
Keyword(s):  
Monoclonal Antibody ◽  
Myosin Heavy Chain ◽  
Heavy Chain ◽  
Contractile Activity ◽  
Pectoral Muscle ◽  
Chicken Muscle ◽  
High K ◽  
Muscle Cultures ◽  
Spontaneous Contractions

The expression of neonatal myosin heavy chain (MHC) was examined in developing embryonic chicken muscle cultures using a monoclonal antibody (2E9) that has been shown to be specific for that isoform (Bandman, E., 1985, Science (Wash. DC), 227: 780-782). After 1 wk in vitro some myotubes could be stained with the antibody, and the number of cells that reacted with 2E9 increased with time in culture. All myotubes always stained with a second monoclonal antibody that reacted with all MHC isoforms (AG19) or with a third monoclonal antibody that reacted with the embryonic but not the neonatal MHC (EB165). Quantitation by ELISA of an extract from 2-wk cultures demonstrated that the neonatal MHC represented between 10 and 15% of the total myosin. The appearance of the neonatal isoform was inhibited by switching young cultures to medium with a higher [K+] which has been shown to block spontaneous contractions of myotubes in culture. Furthermore, if mature cultures that reacted with the neonatal antibody were placed into high [K+] medium, neonatal MHC disappeared from virtually all myotubes within 3 d. The effect of high [K+] medium was reversible. When cultures maintained in high [K+] medium for 2 wk were placed in standard medium, which permitted the resumption of contractile activity, within 24 h cells began to react with the neonatal specific antibody, and by 72 h many myotubes were strongly positive. Since similar results were also obtained by inhibiting spontaneous contractions with tetrodotoxin, we suggest that the development of contractile activity is not only associated with the maturation of myotubes in culture, but may also be the signal that induces the expression of the neonatal MHC.

scholarly journals Rapid dispersal of clustered postsynaptic nuclei following dissociation of skeletal muscle fibers.

1996 ◽  
Vol 199 (11) ◽  
pp. 2359-2367
Author(s):  
C Brösamle ◽  
D P Kuffler
Keyword(s):  
Skeletal Muscle ◽  
Synapse Formation ◽  
Contractile Activity ◽  
Muscle Fibers ◽  
Skeletal Muscle Fibers ◽  
Synaptic Region ◽  
Nuclear Clusters ◽  
Specialized Structure

The vertebrate neuromuscular junction is a highly specialized structure containing many unique proteins and an underlying cluster of nuclei. Part of this specialization results from the expression of the genes for these proteins in nuclei clustered in the postsynaptic region. Contractile activity, as well as molecules located in the synaptic extracellular matrix (ECM), have been implicated in the induction of gene expression in these clustered nuclei. The present experiments were aimed at examining whether the presence of the synaptic ECM and presynaptic cells play a role in maintaining the clustering of the nuclei. We describe the normal distribution of nuclei clustered in the synaptic region of intact adult frog, Rana pipiens, skeletal muscle fibers and show that innervation is not required to maintain the nuclear clusters. Even after long-term (4 week) denervation, the clusters remain unchanged. Dissociation of the muscle fibers with proteases that remove ECM, Schwann cells and other satellite cells from the synaptic sites is followed by a rapid (within approximately 1.5 h) and almost complete dispersal of the clustered nuclei. Attempts to recluster the postsynaptic nuclei by the application of ECM components to muscle fibers in vitro were not successful. We propose that a factor or factors, localized in the synaptic ECM as a result of synapse formation and acting via the transmembrane or cytoplasmic domains of their respective receptors, induces the formation of a specialized cytoskeleton in the postsynaptic region that is capable of pulling in or 'trapping' nuclei. The removal of these factors from the ECM by proteases brings about the disorganization of the cytoskeleton and the freeing of the 'trapped' nuclei.

scholarly journals Simulating the Hydrodynamic Conditions of the Human Ascending Colon: A Digital Twin of the Dynamic Colon Model

Pharmaceutics ◽  
2022 ◽  
Vol 14 (1) ◽  
pp. 184
Author(s):  
Michael Schütt ◽  
Connor O’Farrell ◽  
Konstantinos Stamatopoulos ◽  
Caroline L. Hoad ◽  
Luca Marciani ◽  
...  
Keyword(s):  
Contractile Activity ◽  
Proximal Colon ◽  
Oral Dosage ◽  
Shear Rates ◽  
Digital Twin ◽  
Solid Oral Dosage Forms ◽  
Vitro Model ◽  
In Silico Models ◽  
Oral Dosage Forms

The performance of solid oral dosage forms targeting the colon is typically evaluated using standardised pharmacopeial dissolution apparatuses. However, these fail to replicate colonic hydrodynamics. This study develops a digital twin of the Dynamic Colon Model; a physiologically representative in vitro model of the human proximal colon. Magnetic resonance imaging of the Dynamic Colon Model verified that the digital twin robustly replicated flow patterns under different physiological conditions (media viscosity, volume, and peristaltic wave speed). During local contractile activity, antegrade flows of 0.06–0.78 cm s−1 and backflows of −2.16–−0.21 cm s−1 were measured. Mean wall shear rates were strongly time and viscosity dependent although peaks were measured between 3.05–10.12 s−1 and 5.11–20.34 s−1 in the Dynamic Colon Model and its digital twin respectively, comparable to previous estimates of the USPII with paddle speeds of 25 and 50 rpm. It is recommended that viscosity and shear rates are considered when designing future dissolution test methodologies for colon-targeted formulations. In the USPII, paddle speeds >50 rpm may not recreate physiologically relevant shear rates. These findings demonstrate how the combination of biorelevant in vitro and in silico models can provide new insights for dissolution testing beyond established pharmacopeial methods.

Appearance and evolution of calcium currents and contraction during the early post-fusional stages of rat skeletal muscle cells developing in primary culture

Development ◽  
1993 ◽  
Vol 117 (3) ◽  
pp. 1153-1161
Author(s):  
C. Cognard ◽  
B. Constantin ◽  
M. Rivet-Bastide ◽  
N. Imbert ◽  
C. Besse ◽  
...  
Keyword(s):  
Primary Culture ◽  
Contractile Activity ◽  
Primary Cultures ◽  
Calcium Currents ◽  
Calcium Stores ◽  
Developmental Evolution ◽  
Time To Peak ◽  
Mechanical And Electrical Properties ◽  
Developing Muscle

Primary cultures from enzymatically dissociated satellite cells of newborn rat skeletal muscles enabled developmental in vitro studies of mechanical and electrical properties during the first steps of myogenesis. The present work focused on the appearance, evolution and roles of two types of calcium currents (ICa,T and ICa,L) and of depolarization-induced contractile activity during the early stages of muscle cell development in primary culture. Prefusional mononucleated cells (myoblasts), young myotubes of 1 day (with less than 10 nuclei) or 2–3 days (more than 9 nuclei) and myoballs from 4–6, 7–9, 10–12 and 13–16 days cultures were patch-clamped (whole-cell configuration), and calcium currents and contraction simultaneously recorded. Sodium but not calcium currents could be recorded at the myoblast stage. In young myotubes (1 day), ICa,L was present with high incidence as compared to ICa,T, which was poorly expressed. Contractile responses appeared at the next stage (2-3 days) while the occurrence of ICa,T progressively increased. This developmental evolution of the calcium currents and contraction expression was accompanied by some changes in their characteristics: the ICa,T/ICa,L amplitudes ratio progressively increased and the time-to-peak of contraction progressively decreased with the age of myoballs. Physiological functions for calcium currents in developing muscle are suggested and discussed: ICa,T, which is transiently expressed, could be involved in the pacemaker-like activity while ICa,L could serve as an early contraction triggering mechanism and/or initially to fill and then to maintain the intracellular calcium stores.

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