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Proceedings of the National Academy of... Feb 2019Extraocular muscles contain two types of muscle fibers according to their innervation pattern: singly innervated muscle fibers (SIFs), similar to most skeletal muscle...
Extraocular muscles contain two types of muscle fibers according to their innervation pattern: singly innervated muscle fibers (SIFs), similar to most skeletal muscle fibers, and multiply innervated muscle fibers (MIFs). Morphological studies have revealed that SIF and MIF motoneurons are segregated anatomically and receive different proportions of certain afferents, suggesting that while SIF motoneurons would participate in the whole repertoire of eye movements, MIF motoneurons would contribute only to slow eye movements and fixations. We have tested that proposal by performing single-unit recordings, in alert behaving cats, of electrophysiologically identified MIF and SIF motoneurons in the abducens nucleus. Our results show that both types of motoneuron discharge in relation to eye position and velocity, displaying a tonic-phasic firing pattern for different types of eye movement (saccades, vestibulo-ocular reflex, vergence) and gaze-holding. However, MIF motoneurons presented an overall reduced firing rate compared with SIF motoneurons, and had significantly lower recruitment threshold and also lower eye position and velocity sensitivities. Accordingly, MIF motoneurons could control mainly gaze in the off-direction, when less force is needed, whereas SIF motoneurons would contribute to increase muscle tension progressively toward the on-direction as more force is required. Anatomically, MIF and SIF motoneurons distributed intermingled within the abducens nucleus, with MIF motoneurons being smaller and having a lesser somatic synaptic coverage. Our data demonstrate the functional participation of both MIF and SIF motoneurons in fixations and slow and phasic eye movements, although their discharge properties indicate a functional segregation.
Topics: Animals; Cats; Eye Movements; Humans; Motor Neurons; Muscle Fibers, Skeletal; Muscle Tonus; Muscle, Skeletal; Oculomotor Muscles; Saccades
PubMed: 30760592
DOI: 10.1073/pnas.1818524116 -
Cardiovascular Therapeutics Apr 2012Abnormal coronary vasoconstriction, or coronary spasm, can be the result of several factors, including local and neuroendocrine aberrations. It can manifest clinically... (Review)
Review
Abnormal coronary vasoconstriction, or coronary spasm, can be the result of several factors, including local and neuroendocrine aberrations. It can manifest clinically as a coronary syndrome and plays an important role in the genesis of myocardial ischemia. Over the past half century, coronary angiography allowed the in vivo demonstration of spasm in patients who fit the initial clinical description of the condition as reported by Prinzmetal et al. Several clinical, basic, and more recently, genetic studies have provided insight into the pathogenesis, manifestations, and therapy of this condition. It is not uncommonly encountered in patients with coronary syndromes and absence of clearly pathologic lesions on angiography. Provocation tests utilizing pharmacologic and nonpharmacologic stimuli combined with imaging (echocardiography or coronary angiography) can help make the correct diagnosis. The use of calcium channel blockers and long-acting nitrates is currently considered standard of care and the overall prognosis appears to be good. The recent discovery of genetic abnormalities predisposing to abnormal spasm of the coronaries has stimulated interest in the development of targeted therapies for the management of this condition.
Topics: Angina Pectoris, Variant; Cardiac Catheterization; Chest Pain; Coronary Angiography; Coronary Vasospasm; Coronary Vessels; Humans; Muscle Tonus; Prognosis; Ultrasonography; Vasoconstriction
PubMed: 20946324
DOI: 10.1111/j.1755-5922.2010.00235.x -
Drug Discoveries & Therapeutics May 2017Clove oil is used in fish anesthesia and expected to have a mechanism via glutamic receptor. The present study explores the activities of clove oil and its major...
Clove oil is used in fish anesthesia and expected to have a mechanism via glutamic receptor. The present study explores the activities of clove oil and its major compound, eugenol, in comparison with L-glutamic acid on glutamic receptor of silkworm muscle and fish anesthesia. It was found that clove oil and eugenol had similar effects to L-glutamic acid on inhibition of silkworm muscle contraction after treated with D-glutamic acid and kainic acid. Anesthetic activity of the test samples was investigated in goldfish. The results demonstrated that L-glutamic acid at 20 and 40 mM could induce the fish to stage 3 of anesthesia that the fish exhibited total loss of equilibrium and muscle tone, whereas clove oil and eugenol at 60 ppm could induce the fish to stage 4 of anesthesia that the reflex activity of the fish was lost. These results suggest that clove oil and eugenol have similar functional activities and mechanism to L-glutamic acid on muscle contraction and fish anesthesia.
Topics: Anesthesia; Animals; Anti-Infective Agents; Bombyx; Clove Oil; Eugenol; Glutamic Acid; Goldfish; Kainic Acid; Muscle Contraction; Muscle Tonus; Postural Balance; Receptors, Glutamate; Reflex
PubMed: 28458297
DOI: 10.5582/ddt.2017.01012 -
Experimental Physiology Jan 2008Epoxygenases, particularly of the CYP2C and CYP2J families, are important lipid-metabolizing enzymes. Epoxygenases are found throughout the cardiovascular system where... (Review)
Review
Epoxygenases, particularly of the CYP2C and CYP2J families, are important lipid-metabolizing enzymes. Epoxygenases are found throughout the cardiovascular system where their lipid products, particularly the epoxyeicosatrienoic acids (EETs), which are arachidonic acid metabolites, have the potential to regulate vascular tone, cellular proliferation, migration, inflammation and cardiac function. The receptors for EETs are, however, poorly understood. The peroxisome proliferator-activated receptors (PPARs) are a family of three (alpha, beta/delta and gamma) nuclear receptors that are activated by lipid metabolites. Activation of PPAR alpha and PPAR gamma, similar to the longer term effects of EETs, causes the inhibition of vascular cell proliferation, migration and inflammation. Interestingly, EETs and their metabolites have recently been found to active both PPAR alpha and PPAR gamma. The epoxygenase-EET-PPAR pathway may therefore represent a novel endogenous protective pathway by which short-lived lipid mediators control vascular cell activation.
Topics: Animals; Blood Vessels; Cell Movement; Cell Proliferation; Cytochrome P-450 CYP2J2; Cytochrome P-450 Enzyme System; Eicosanoic Acids; Heart; Humans; Inflammation; Mammals; Muscle Tonus; Muscle, Smooth, Vascular; Oxygenases; Peroxisome Proliferator-Activated Receptors
PubMed: 17872966
DOI: 10.1113/expphysiol.2007.038612 -
The Journal of Neuroscience : the... Aug 1990Stimulation of the midbrain retrorubral (RRN), ventral paralemniscal tegmental field (vFTP), reticular tegmental (TRN), and pedunculopontine tegmental (PPN) nuclei was...
Stimulation of the midbrain retrorubral (RRN), ventral paralemniscal tegmental field (vFTP), reticular tegmental (TRN), and pedunculopontine tegmental (PPN) nuclei was found to produce bilateral suppression of muscle tone in the unanesthetized, decerebrate animal. The RRN is the most rostral area shown to produce such suppression. This muscle tone suppression was frequency- and intensity-dependent. At low stimulus intensities, bilateral suppression was produced at these sites. At higher current and frequency levels, 2 types of muscle responses were found, excitation in PPN and RRN and initial suppression followed by excitation in TRN and vFTP. The mean latency to muscle tone suppression was not significantly different in TRN (36.8 msec) and RRN (36.5 msec). However, muscle tone suppression latency was significantly shorter in vFTP (31 msec) and PPN (27.1 msec). In addition to muscle tone suppression, stepping-like activity could be elicited at the same points by consecutive train stimulations in PPN and single train stimulation in TRN and vFTP. Thus, systems producing atonia are colocalized with those producing locomotion. We hypothesize that the midbrain atonia regions control more caudal regions producing muscle tone suppression in REM sleep, and that the locomotor and atonia eliciting regions are normally coactivated during REM sleep.
Topics: Animals; Brain Mapping; Cats; Differential Threshold; Electric Stimulation; Female; Locomotion; Male; Mesencephalon; Muscle Tonus; Pons; Reticular Formation
PubMed: 2388085
DOI: 10.1523/JNEUROSCI.10-08-02727.1990 -
Respiratory Physiology & Neurobiology Aug 2017Vagal innervations have a great role in the respiratory function and are the main route of signal transmission from respiratory neural centers into the trachea and...
Vagal innervations have a great role in the respiratory function and are the main route of signal transmission from respiratory neural centers into the trachea and others conducting airways. We have investigated the role of central mechanisms related to vagal neural pathways and the cholinergic outflow in tracheobronchial smooth muscle tone and lung mechanics parameters. Parameters of lung mechanics such as lung resistance (RL), dynamic compliance (Cdyn) and pressure in bypassed tracheal segment (Ptseg) were measured before and after vagotomy and asphyxia test. Before vagotomy (BV), the control measurements were obtained and physostigmine was administered systemically, in increasing dose 10, 40 and 100μg/kg body weight (bw) with 15min interval between doses. After vagotomy (AV), administration of physostigmine with the same doses as BV has been done and the asphyxia challenge was conducted as per study protocol. The values of Ptseg and RL after physostigmine administration, BV vs. AV, respectively, at maximal dose of 100μg/kg bw were 32.5±3.3cm HO, and 10.6±1.5cm HO (p<0.0001); 0.16±0.04cm HO/mL/s, and 0.067±0.006cm HO/mL/s AV (P<0.05). The Cydn values were affected after physostigmine administration only at the lowest dose of 10μg/kg bw, and BV was 0.75±0.05mL/cm HO vs. 0.53±0.04mL/cm HO AV (P<0.004). Cholinergic outflow produced increases in tracheal tone, lung resistance and a decrease in dynamic compliance before, but not after vagotomy. Our results show the high impact of central neuronal mechanism in parameters of lung mechanics and respiration. This study indicates that vagal nerves have a crucial role, in the transmission of impulses initiated from central nervous system, in regulating the respiration by contraction or relaxation of airway smooth muscle tone.
Topics: Airway Resistance; Animals; Cholinesterase Inhibitors; Cholinesterases; Dose-Response Relationship, Drug; Ferrets; Lung; Male; Models, Animal; Muscle Tonus; Muscle, Smooth; Neuromuscular Agents; Physostigmine; Respiratory System Agents; Trachea; Vagotomy; Vagus Nerve
PubMed: 28445778
DOI: 10.1016/j.resp.2017.04.005 -
Proceedings of the National Academy of... Jun 2012Skeletal muscle is widely perceived as nearly incompressible despite the fact that blood and lymphatic vessels within the endomysial and perimysial spaces undergo...
Skeletal muscle is widely perceived as nearly incompressible despite the fact that blood and lymphatic vessels within the endomysial and perimysial spaces undergo significant changes in diameter and length during stretch and contraction. These fluid shifts between fascicle and interstitial compartments have proved extremely difficult to measure. In this paper, we propose a theoretical framework based on a space-filling hexagonal fascicle array to provide predictions of the displacement of blood and lymph into and out of the muscle's endomysium and perimysium during stretch and contraction. We also use this model to quantify the distribution of blood and initial lymphatic (IL) vessels within a fascicle and its perimysial space using data for the rat spinotrapezius muscle. On average, there are 11 muscle fibers, 0.4 arteriole/venule pairs, and 0.2 IL vessels per fascicle. The model predicts that the blood volume in the endomysial space increases 24% and decreases 22% for a 20% contraction and stretch, respectively. However, these significant changes in blood volume in the endomysium produce a change of only ∼2% in fascicle cross-sectional area. In contrast, the entire muscle deviates from isovolumetry by 7% and 6% for a 20% contraction and stretch, respectively, largely attributable to the significantly larger blood volume changes that occur in the perimysial space. This suggests that arcade blood vessels in the perimysial space provide the primary pumping action required for the filling and emptying of ILs during muscular contraction and stretch.
Topics: Animals; Biomechanical Phenomena; Lymph; Models, Biological; Muscle Contraction; Muscle Tonus; Muscle, Skeletal; Rats; Regional Blood Flow
PubMed: 22615376
DOI: 10.1073/pnas.1206398109 -
BMC Anesthesiology Nov 2023The quantitative assessment of muscle stiffness or weakness is essential for medical care. Shear wave elastography is non-invasive ultrasound method and provides... (Observational Study)
Observational Study
OBJECTIVES
The quantitative assessment of muscle stiffness or weakness is essential for medical care. Shear wave elastography is non-invasive ultrasound method and provides quantitative information on the elasticity of soft tissue. However, the universal velocity scale for quantification has not been developed. The aim of the study is to determine the shear wave velocities of abdominal muscle during anesthetic induction and to identify methods to cancel the effects of confounders for future development in the quantitative assessment of muscle tone using the universal scale.
METHODS
We enrolled 75 adult patients undergoing elective surgery with ASA-PS I - III in the period between December 2018 and March 2021. We measured and calculated the shear wave velocity (SWV) before and after opioid administration (i.e., the baseline at rest and opioid-induced rigidity condition), and after muscle relaxant administration (i.e., zero reference condition). The SWV value was adjusted for the subcutaneous fat thickness by our proposed corrections. The SWVs after the adjustment were compared among the values in baseline, rigidity, and relaxation using one-way repeated-measures ANOVA and post hoc Tukey-Kramer test. A p-value of < 0.05 was considered to be statistically significant. UMIN Clinical Trials Registry identifier UMIN000034692, registered on October 30, 2018.
RESULTS
The SWVs in the baseline, opioid-induced rigidity, and muscle relaxation conditions after the adjustment were 2.08 ± 0.48, 2.41 ± 0.60, and 1.79 ± 0.30 m/s, respectively (p < 0.001 at all comparisons).
CONCLUSION
The present study suggested that the SWV as reference was 1.79 m/s and that the SWVs at rest and opioid-induced rigidity were ~ 10% and ~ 30% increase from the reference, respectively. The SWV adjusted for the subcutaneous fat thickness may be scale points for the assessment of muscle tone.
Topics: Adult; Humans; Muscle, Skeletal; Muscle Tonus; Analgesics, Opioid; Elasticity Imaging Techniques; Anesthetics
PubMed: 38031018
DOI: 10.1186/s12871-023-02358-9 -
The Journal of Neuroscience : the... Feb 2011Extraocular muscle tension associated with spontaneous eye movements has a pulse-slide-step profile similar to that of motoneuron firing rate. Existing models only...
Extraocular muscle tension associated with spontaneous eye movements has a pulse-slide-step profile similar to that of motoneuron firing rate. Existing models only relate motoneuron firing to eye position, velocity and acceleration. We measured and quantitatively compared lateral rectus muscle force and eye position with the firing of abducens motoneurons in the cat to determine fundamental encoding correlations. During fixations (step), muscle force increased exponentially with eccentric eye position, consistent with a model of estimate ensemble motor innervation based on neuronal sensitivities and recruitment order. Moreover, firing rate in all motoneurons tested was better related to eye position than to muscle tension during fixations. In contrast, during the postsaccadic slide phase, the time constant of firing rate decay was closely related to that of muscle force decay, suggesting that all motoneurons encode muscle tension as well. Discharge characteristics of abducens motoneurons formed overlapping clusters of phasic and tonic motoneurons, thus, tonic units recruited earlier and had a larger slide signal. We conclude that the slide signal is a discharge characteristic of the motoneuron that controls muscle tension during the postsaccadic phase and that motoneurons are specialized for both tension and position-related properties. The organization of signal content in the pool of abducens motoneurons from the very phasic to the very tonic units is possibly a result of the differential trophic background received from distinct types of muscle fibers.
Topics: Abducens Nerve; Action Potentials; Animals; Biomechanical Phenomena; Biophysics; Cats; Cluster Analysis; Electric Stimulation; Electromyography; Eye Movements; Female; Motor Neurons; Muscle Tonus; Oculomotor Muscles; Recruitment, Neurophysiological
PubMed: 21307263
DOI: 10.1523/JNEUROSCI.5416-10.2011 -
Medicina (Kaunas, Lithuania) Sep 2019Functional electrical stimulation (FES) has shown good results in improving static and dynamic sitting balance in persons with spinal cord injuries. There is limited...
The Effect of Functional Electrical Stimulation and Therapeutic Exercises on Trunk Muscle Tone and Dynamic Sitting Balance in Persons with Chronic Spinal Cord Injury: A Crossover Trial.
Functional electrical stimulation (FES) has shown good results in improving static and dynamic sitting balance in persons with spinal cord injuries. There is limited information about how regular surface FES combined with therapeutic exercise (TE) affect dynamic sitting balance and muscle tone. The objective of this study was to evaluate the effectiveness of a six-week physical therapy program consisting of FES and TE on muscle tone and sitting balance in persons with spinal cord injury (SCI). It was also important to explore the relationship between muscle tone and dynamic sitting balance. The third objective was to assess the change of characteristics over a six month period, when no intervention was carried out. Five men with SCI were alternately allocated to two study groups: SCI_FES+TE and SCI_TE. Eight healthy control group participants were recruited to collect reference data. SCI participants' intervention lasted for six weeks in their homes. SCI_FES+TE conducted exercises with FES applied on erector spinae (ES) and rectus abdominis (RA) muscles. SCI_TE conducted exercises only. Muscle oscillation frequency (MOF; characterizing muscle tone) and limits of stability (LOS; characterizing sitting balance) were measured. A crossover study design was used. The time between the initial intervention and the crossover was seven months (ClinicalTrials registration ID NCT03517787). MOF in SCI_FES+TE increased by 6.0% for ES and 6.1% for RA muscles. LOS of flexion increased 30.1% in SCI_FES+TE. Increase in lateral directions was similar for both study groups. Moderate to high negative correlation was found between MOF and LOS. After seven months, MOF of ES decreased 0.8%, MOF or RA decreased 1.4%, LOS of flexion decreased 31.9%, and LOS of lateral flexion to the left decreased 46.4%. The six-week therapy program combining FES and TE increased trunk muscle tone and dynamic sitting balance in flexion more than TE alone. Higher antagonist muscle tone negatively affects dynamic sitting balance and center of pressure (COP) trajectory distance in various directions. After seven months, a slight decline in trunk muscles tone values and an extensive decrease in sitting balance values were noticed.
Topics: Adult; Case-Control Studies; Combined Modality Therapy; Cross-Over Studies; Electric Stimulation Therapy; Exercise Therapy; Humans; Male; Muscle Tonus; Postural Balance; Reference Values; Sitting Position; Spinal Cord Injuries
PubMed: 31546613
DOI: 10.3390/medicina55100619