A minimal constraint device for imaging nuclei in live Drosophila contractile larval muscles reveals novel nuclear mechanical dynamics

Lab on a Chip ◽  
2020 ◽  
Vol 20 (12) ◽  
pp. 2100-2112 ◽  
Author(s):  
Dana Lorber ◽  
Ron Rotkopf ◽  
Talila Volk
Keyword(s):  
Muscle Contraction ◽  
Muscle Contractions ◽  
Mechanical Dynamics ◽  
Minimal Constraint

Muscle contractions produce reiterated cytoplasmic mechanical variations, which potentially influence nuclear mechanotransduction, however information regarding the dynamics of muscle nuclei in the course of muscle contraction is still missing.

Timed synchronization of muscle contraction to heartbeat enhances muscle hyperemia

2020 ◽  
Vol 128 (4) ◽  
pp. 805-812
Author(s):  
Gaia Giuriato ◽  
Stephen J. Ives ◽  
Cantor Tarperi ◽  
Lorenzo Bortolan ◽  
Federico Ruzzante ◽  
...  
Keyword(s):  
Blood Flow ◽  
Muscle Contraction ◽  
Blood Velocity ◽  
Muscle Contractions ◽  
Velocity Spectrum ◽  
Functional Hyperemia ◽  
Central Hemodynamics ◽  
Active Muscle ◽  
Vascular Conductance ◽  
Significant Difference

Blood flow (BF) to exercising muscles is susceptible to variations of intensity, and duration of skeletal muscle contractions, cardiac cycle, blood velocity, and vessel dilation. During cyclic muscle activity, these elements may change proportionally with or without direct optimal temporal alignment, likely influencing BF to active muscle. Ideally, the pulsed delivery of blood to active muscle timed with the inactive phase of muscle duty-cycle would enhance the peak and average BF. To investigate the phenomenon of muscle contraction and pulse synchronicity, electrically evoked muscle contractions (trains of 20 Hz, 200-ms duration) were synchronized with each systolic phase of the anterograde blood velocity spectrum (aBVS). Specifically, unilateral quadriceps contractions matched in-phase (IP) with the aBVS were compared with contractions matched out-of-phase (OP) with the aBVS in 10 healthy participants (26 ± 3 yr). During each trial, femoral BF of the contracting limb and central hemodynamics were recorded for 5 min with an ultrasound Doppler, a plethysmograph, and a cardioimpedance device. At steady state (5th min) IP BF (454 ± 30 mL/min) and vascular conductance (4.3 ± 0.2 mL·min−1·mmHg−1), and OP MAP (108 ± 2 mmHg) were significantly lower ( P < 0.001) in comparison to OP BF (784 ± 25 mL/min) and vascular conductance (6.7 ± 0.2 mL·min−1·mmHg−1), and IP MAP (113 ± 3 mmHg). On the contrary, no significant difference (all, P > 0.05) was observed between IP and OP central hemodynamics (HR: 79 ± 10 vs. 76 ± 11 bpm, CO: 8.0 ± 1.6 vs. 7.3 ± 1.6 L/min), and ventilatory patterns (V̇e:14 ± 2 vs. 14 ± 1 L/min, V̇o2:421 ± 70 vs. 397 ± 34 mL/min). The results suggest that muscle contractions occurring during OP that do not interfere with aBVS elicit a maximization of muscle functional hyperemia. NEW & NOTEWORTHY When muscle contraction is synchronized with the pulsed delivery of blood flow to active muscle, muscle functional hyperemia can be either maximized or minimized. This suggests a possibility to couple different strategies to enhance the acute and chronic effects of exercise on the cardiovascular system.

Effects of endothelin and nitric oxide on cardiac muscle functions in experimental septic shock model

2015 ◽  
Vol 35 (3) ◽  
pp. 267-275 ◽  
Author(s):  
EK Ozer ◽  
AB Iskit
Keyword(s):  
Nitric Oxide ◽  
Septic Shock ◽  
Muscle Contraction ◽  
Cardiac Muscle ◽  
Papillary Muscle ◽  
Cecal Ligation ◽  
Muscle Contractions ◽  
Albino Rats ◽  
Beat Rate

We aimed to investigate the possible roles of nitric oxide (NO) and endothelin on the changes of cardiac muscle function in both hyper- and hypodynamic septic shock periods. Cecal ligation and puncture was performed in 50 Wistar albino rats to induce septic shock. Changes in atrium and right ventricle papillary muscle contractions, atrium beat rate, adrenergic and cholinergic responses in these tissues were evaluated in vitro. Atrium beat rate increased in hypodynamic period ( p < 0.001) that was reversed by bosentan ( p < 0.001) and NG-nitro-l-arginine methylester (l-NAME; p < 0.05). Atrium contractions decreased in both hyper- and hypodynamic periods ( p < 0.001) that were partially ameliorated by bosentan in both periods ( p < 0.01) and only in hypodynamic period by l-NAME ( p < 0.001). l-NAME increased papillary muscle contractions in both periods ( p < 0.01), but bosentan increased it only in hyperdynamic period ( p < 0.01). Bosentan and l-NAME increased potency of isoproterenol on atrium beat rate in both periods and increased carbachol potency on atrium beat rate and atrium contraction amplitude only in hypodynamic period. Bosentan increased atrium contraction response to isoproterenol in hypodynamic period ( p < 0.05). Papillary muscle contraction response to isoproterenol increased in hypodynamic period ( p < 0.05). l-NAME increased papillary muscle contraction response to carbachol in both periods ( p < 0.01, p < 0.05, respectively). These results show that NO and endothelin may play a role in positive inotropic and negative chronotropic effects for atrium in septic shock. Bosentan and l-NAME may change potency and efficacy of isoproterenol and carbachol via upregulation of adrenergic and cholinergic receptors and/or through post receptor factors.

Serotonergic and Peptidergic Modulation of the Buccal Mass Protractor Muscle (I2) in Aplysia

2000 ◽  
Vol 84 (6) ◽  
pp. 2810-2820 ◽  
Author(s):  
I. Hurwitz ◽  
E. C. Cropper ◽  
F. S. Vilim ◽  
V. Alexeeva ◽  
A. J. Susswein ◽  
...  
Keyword(s):  
Muscle Contraction ◽  
Relaxation Rate ◽  
Behavioral Plasticity ◽  
Muscle Relaxation ◽  
Firing Frequency ◽  
Muscle Contractions ◽  
Contraction Amplitude ◽  
Neuronal Processes ◽  
Neuromuscular Systems ◽  
High Concentrations

Plasticity of Aplysia feeding has largely been measured by noting changes in radula protraction. On the basis of previous work, it has been suggested that peripheral modulation may contribute to behavioral plasticity. However, peripheral plasticity has not been demonstrated in the neuromuscular systems that participate in radula protraction. Therefore in this study we investigated whether contractions of a major radula protraction muscle (I2) are subject to modulation. We demonstrate, first, that an increase in the firing frequency of the cholinergic I2 motoneurons will increase the amplitude of the resulting muscle contraction but will not modulate its relaxation rate. We show, second, that neuronal processes on the I2 muscle are immunoreactive to myomodulin (MM), RFamide, and serotonin (5-HT), but not to small cardioactive peptide (SCP) or buccalin. The I2 motoneurons B31, B32, B61, and B62 are not immunoreactive to RFamide, 5-HT, SCP, or buccalin. However, all four cells are MM immunoreactive and are capable of synthesizing MMa. Third, we show that the bioactivity of the different modulators is somewhat different; while the MMs (i.e., MMa and MMb) and 5-HT increase I2 muscle relaxation rate, and potentiate muscle contraction amplitude, MMa, at high concentrations, depresses muscle contractions. Fourth, our data suggest that cAMP at least partially mediates effects of modulators on contraction amplitude and relaxation rate.

Sustained Muscle Contractions Maintained by Autonomous Neuronal Activity Within the Human Spinal Cord

2003 ◽  
Vol 90 (4) ◽  
pp. 2090-2097 ◽  
Author(s):  
Daichi Nozaki ◽  
Noritaka Kawashima ◽  
Yu Aramaki ◽  
Masami Akai ◽  
Kimitaka Nakazawa ◽  
...  
Keyword(s):  
Spinal Cord ◽  
Muscle Contraction ◽  
Soleus Muscle ◽  
Primary Motor Cortex ◽  
Human Subjects ◽  
Silent Period ◽  
Muscle Contractions ◽  
Electromyographic Activity ◽  
Human Spinal Cord ◽  
Train Stimulation

It is well known that muscle contraction can be easily evoked in the human soleus muscle by applying single-pulse electrical stimulation to the tibial nerve at the popliteal fossa. We herein reveal the unexpected phenomenon of muscle contractions that can be observed when train stimulation is used instead. We found, in 11 human subjects, that transient electrical train stimulation (1-ms pulses, 50 Hz, 2 s) was able to induce sustained muscle contractions in the soleus muscle that outlasted the stimulation period for greater than 1 min. Subjects were unaware of their own muscle activity, suggesting that this is an involuntary muscle contraction. In fact, the excitability of the primary motor cortex (M1) with the sustained muscle contractions evaluated by transcranial magnetic stimulation was lower than the excitability with voluntary muscle contractions even when both muscle contraction levels were matched. This finding indicates that M1 was less involved in maintaining the muscle contractions. Furthermore, the muscle contractions did not come from spontaneous activity of muscle fibers or from reverberating activity within closed neuronal circuits involving motoneurons. These conclusions were made based on the respective evidence: 1) the electromyographic activity was inhibited by stimulation of the common peroneal nerve that has inhibitory connections to the soleus motoneuron pool and 2) it was not abolished after stopping the reverberation (if any) for approximately 100 ms by inducing the silent period that followed an H-reflex. These findings indicate that the sustained muscle contractions induced in this study are most likely to be maintained by autonomous activity of motoneurons and/or interneurons within the human spinal cord.

Static muscle contraction reflexly increases adrenal sympathetic nerve activity in rats

1991 ◽  
Vol 261 (5) ◽  
pp. R1307-R1312 ◽  
Author(s):  
J. Vissing ◽  
L. B. Wilson ◽  
J. H. Mitchell ◽  
R. G. Victor
Keyword(s):  
Adrenal Gland ◽  
Muscle Contraction ◽  
Neuromuscular Blockade ◽  
Sympathetic Nerve ◽  
Sympathetic Nerve Activity ◽  
Tibial Nerve ◽  
Muscle Contractions ◽  
Nerve Activity ◽  
Ganglionic Blockade ◽  
Alpha Chloralose

Little is known about the mechanisms responsible for activation of sympathoadrenal function during exercise. We hypothesized that sympathoadrenal discharge is activated at the onset of exercise by a reflex arising in the contracting muscle. Adrenal sympathetic nerve activity (SNA) was recorded during 1 min stimulation of the tibial nerve at two times motor threshold, before and during neuromuscular blockade, in 12 alpha-chloralose-anesthetized rats. Static muscle contractions, induced by stimulation before neuromuscular blockade, were repeated during ganglionic blockade (n = 6) to specifically test reflex activation of preganglionic activity to the adrenal gland. During static contraction, adrenal SNA rapidly increased (P less than 0.05) to a maximum of 89 +/- 12% above basal and then declined, reaching basal levels after 30 s of muscle contraction. Tibial nerve stimulation during neuromuscular blockade had no effect on adrenal SNA. In most rats, adrenal SNA decreased with ganglionic blockade, indicating postganglionic as well as preganglionic innervation of the adrenal gland. During ganglionic blockade, static muscle contractions elicited a 140 +/- 21% increase in adrenal preganglionic SNA. In conclusion, static muscle contraction reflexly increases SNA to the adrenal gland, providing a mechanism for sympathoadrenal activation at the onset of exercise.

scholarly journals Mechanical effects of muscle contraction increase intravascular ATP draining quiescent and active skeletal muscle in humans

2013 ◽  
Vol 114 (8) ◽  
pp. 1085-1093 ◽  
Author(s):  
Anne R. Crecelius ◽  
Brett S. Kirby ◽  
Jennifer C. Richards ◽  
Frank A. Dinenno
Keyword(s):  
Skeletal Muscle ◽  
Blood Flow ◽  
Muscle Contraction ◽  
Cuff Pressure ◽  
Muscle Blood Flow ◽  
Muscle Contractions ◽  
Luciferase Assay ◽  
Metabolic Demand ◽  
Mechanical Effects

Intravascular adenosine triphosphate (ATP) evokes vasodilation and is implicated in the regulation of skeletal muscle blood flow during exercise. Mechanical stresses to erythrocytes and endothelial cells stimulate ATP release in vitro. How mechanical effects of muscle contractions contribute to increased plasma ATP during exercise is largely unexplored. We tested the hypothesis that simulated mechanical effects of muscle contractions increase [ATP]venous and ATP effluent in vivo, independent of changes in tissue metabolic demand, and further increase plasma ATP when superimposed with mild-intensity exercise. In young healthy adults, we measured forearm blood flow (FBF) (Doppler ultrasound) and plasma [ATP]v (luciferin-luciferase assay), then calculated forearm ATP effluent (FBF×[ATP]v) during rhythmic forearm compressions (RFC) via a blood pressure cuff at three graded pressures (50, 100, and 200 mmHg; Protocol 1; n = 10) and during RFC at 100 mmHg, 5% maximal voluntary contraction rhythmic handgrip exercise (RHG), and combined RFC + RHG ( Protocol 2; n = 10). [ATP]v increased from rest with each cuff pressure (range 144–161 vs. 64 ± 13 nmol/l), and ATP effluent was graded with pressure. In Protocol 2, [ATP]v increased in each condition compared with rest (RFC: 123 ± 33; RHG: 51 ± 9; RFC + RHG: 96 ± 23 vs. Mean Rest: 42 ± 4 nmol/l; P < 0.05), and ATP effluent was greatest with RFC + RHG (RFC: 5.3 ± 1.4; RHG: 5.3 ± 1.1; RFC + RHG: 11.6 ± 2.7 vs. Mean Rest: 1.2 ± 0.1 nmol/min; P < 0.05). We conclude that the mechanical effects of muscle contraction can 1) independently elevate intravascular ATP draining quiescent skeletal muscle without changes in local metabolism and 2) further augment intravascular ATP during mild exercise associated with increases in metabolism and local deoxygenation; therefore, it is likely one stimulus for increasing intravascular ATP during exercise in humans.

The Neuromuscular Transform: The Dynamic, Nonlinear Link Between Motor Neuron Firing Patterns and Muscle Contraction in Rhythmic Behaviors

2000 ◽  
Vol 83 (1) ◽  
pp. 207-231 ◽  
Author(s):  
Vladimir Brezina ◽  
Irina V. Orekhova ◽  
Klaudiusz R. Weiss
Keyword(s):  
Nervous System ◽  
Motor Neuron ◽  
Muscle Contraction ◽  
Firing Pattern ◽  
Systems Approach ◽  
Muscle Contractions ◽  
Neuron Firing ◽  
Firing Patterns ◽  
Motor Commands ◽  
Rhythmic Behaviors

The nervous system issues motor commands to muscles to generate behavior. All such commands must, however, pass through a filter that we call here the neuromuscular transform (NMT). The NMT transforms patterns of motor neuron firing to muscle contractions. This work is motivated by the fact that the NMT is far from being a straightforward, transparent link between motor neuron and muscle. The NMT is a dynamic, nonlinear, and modifiable filter. Consequently motor neuron firing translates to muscle contraction in a complex way. This complexity must be taken into account by the nervous system when issuing its motor commands, as well as by us when assessing their significance. This is the first of three papers in which we consider the properties and the functional role of the NMT. Physiologically, the motor neuron–muscle link comprises multiple steps of presynaptic and postsynaptic Ca2+ elevation, transmitter release, and activation of the contractile machinery. The NMT formalizes all these into an overall input-output relation between patterns of motor neuron firing and shapes of muscle contractions. We develop here an analytic framework, essentially an elementary dynamical systems approach, with which we can study the global properties of the transformation. We analyze the principles that determine how different firing patterns are transformed to contractions, and different parameters of the former to parameters of the latter. The key properties of the NMT are its nonlinearity and its time dependence, relative to the time scale of the firing pattern. We then discuss issues of neuromuscular prediction, control, and coding. Does the firing pattern contain a code by means of which particular parameters of motor neuron firing control particular parameters of muscle contraction? What information must the motor neuron, and the nervous system generally, have about the periphery to be able to control it effectively? We focus here particularly on cyclical, rhythmic contractions which reveal the principles particularly clearly. Where possible, we illustrate the principles in an experimentally advantageous model system, the accessory radula closer (ARC)–opener neuromuscular system of Aplysia. In the following papers, we use the framework developed here to examine how the properties of the NMT govern functional performance in different rhythmic behaviors that the nervous system may command.

scholarly journals Topical application of Zanthoxylum piperitum extract improves lateral canthal rhytides by inhibiting muscle contractions

2020 ◽  
Vol 10 (1) ◽  
Author(s):  
Wooseon Hwang ◽  
Daehyun Kim ◽  
Oh Sun Kwon ◽  
Yun-Sun Kim ◽  
Byungjun Ahn ◽  
...  
Keyword(s):  
Muscle Contraction ◽  
Synergistic Effects ◽  
Botulinum Toxin Type A ◽  
Botulinum Toxin Type ◽  
Electrical Signal ◽  
Muscle Contractions ◽  
Model Systems ◽  
In Vitro Assays ◽  
Zanthoxylum Piperitum

AbstractFacial wrinkles are the predominant phenotypes of skin aging. To date, one of the most effective ways to improve wrinkles is botulinum toxin type A (BoNT/A) injection, which inhibits muscle contractions by reducing acetylcholine release from neurons. However, since BoNT/A is a hazardous neurotoxin, the injection can only be performed by medical doctors and the procedure is only possible through invasive injection, causing inconveniences such as pain. To overcome these inconveniences, we tried to find a way to reduce wrinkles non-invasively via mechanisms similar to BoNT/A. We first designed in vitro assays to test BoNT/A-like muscle contraction inhibition in two different model systems. By using the assays, we identified Zanthoxylum piperitum (Z. piperitum) fruit extract as a BoNT-like reagent (27.7% decrease of muscle contraction rates by 1000 ppm of Z. piperitum extract treatment). Next, we determined mechanisms of how Z. piperitum extract decreases muscle contraction rates and found that the extract treatment inhibits electrical signal transduction in neurons. We also showed that among known components of Z. piperitum extract, quercitrin is responsible for muscle contraction inhibition. We further identified that Z. piperitum extract has synergistic effects with acetyl hexapeptide-8 and BoNT/A light chain, which are well-known BoNT-like peptides. Finally, we showed that topical treatment of the Z. piperitum extract indeed decreases facial wrinkles and treatment of Z. piperitum extract with acetyl hexapeptide-8 has a tendency to improve wrinkles synergistically (14.5% improvement on average). The synergistic effect of the combination is expected to improve wrinkles effectively by implementing the BoNT/A mechanisms in a non-invasive way.

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