Contractile force is transmitted to the skeleton through tendons and aponeuroses, and, although it is appreciated that the mechanocharacteristics of these tissues play an important role for movement performance with respect to energy storage, the association between tendon mechanical properties and the contractile muscle output during high-force movement tasks remains elusive. The purpose of the study was to investigate the relation between the mechanical properties of the connective tissue and muscle performance in maximal isometric and dynamic muscle actions. Sixteen trained men participated in the study. The mechanical properties of the vastus lateralis tendon-aponeurosis complex were assessed by ultrasonography. Maximal isometric knee extensor force and rate of torque development (RTD) were determined. Dynamic performance was assessed by maximal squat jumps and countermovement jumps on a force plate. From the vertical ground reaction force, maximal jump height, jump power, and force-/velocity-related determinants of jump performance were obtained. RTD was positively related to the stiffness of the tendinous structures (r = 0.55, P < 0.05), indicating that tendon mechanical properties may account for up to 30% of the variance in RTD. A correlation was observed between stiffness and maximal jump height in squat jumps and countermovement jumps (r = 0.64, P < 0.05 and r = 0.55, P < 0.05). Power, force, and velocity parameters obtained during the jumps were significantly correlated to tendon stiffness. These data indicate that muscle output in high-force isometric and dynamic muscle actions is positively related to the stiffness of the tendinous structures, possibly by means of a more effective force transmission from the contractile elements to the bone.

Muscle performance during maximal isometric and dynamic contractions is influenced by the stiffness of the tendinous structures

Autonomic nerves in most mammalian species mediate both contractions and relaxations of airway smooth muscle. Cholinergic-parasympathetic nerves mediate contractions, whereas adrenergic-sympathetic and/or noncholinergic parasympathetic nerves mediate relaxations. Sympathetic-adrenergic innervation of human airway smooth muscle is sparse or nonexistent based on histological analyses and plays little or no role in regulating airway caliber. Rather, in humans and in many other species, postganglionic noncholinergic parasympathetic nerves provide the only relaxant innervation of airway smooth muscle. These noncholinergic nerves are anatomically and physiologically distinct from the postganglionic cholinergic parasympathetic nerves and differentially regulated by reflexes. Although bronchopulmonary vagal afferent nerves provide the primary afferent input regulating airway autonomic nerve activity, extrapulmonary afferent nerves, both vagal and nonvagal, can also reflexively regulate autonomic tone in airway smooth muscle. Reflexes result in either an enhanced activity in one or more of the autonomic efferent pathways, or a withdrawal of baseline cholinergic tone. These parallel excitatory and inhibitory afferent and efferent pathways add complexity to autonomic control of airway caliber. Dysfunction or dysregulation of these afferent and efferent nerves likely contributes to the pathogenesis of obstructive airways diseases and may account for the pulmonary symptoms associated with extrapulmonary disorders, including gastroesophageal reflux disease, cardiovascular disease, and rhinosinusitis.

Reflex regulation of airway smooth muscle tone.

Neurodevelopmental disorders (NDDs) are defined as a group of disorders caused by changes in early brain development, resulting in behavioral and cognitive alterations in sensory and motor systems, speech, and language. NDDs affect approximately 1-2% of the general population. Up to 80% of children with NDDs are reported to have disrupted sleep; subsequent deleterious effects on daytime behaviors, cognition, growth, and overall development of the child are commonly reported. Examples of NDDs discussed in this review include autism spectrum disorder, cerebral palsy, Rett syndrome, Angelman syndrome, Williams syndrome, and Smith-Magenis syndrome. The etiology of sleep disorders in children with NDDs is largely heterogeneous and disease specific. The diagnosis and management of sleep disorders in this population are complex, and little high-quality data exist to guide a consistent approach to therapy. Managing sleep disorders in children with NDDs is critical both for the child and for the family but is often frustrating due to the refractory nature of the problem. Sleep hygiene must be implemented as first-line therapy; if sleep hygiene alone fails, it should be combined with pharmacologic management. The available evidence for the use of common pharmacologic interventions, such as iron supplementation and melatonin, as well as less common interventions, such as melatonin receptor agonists, clonidine, gabapentin, hypnotics, trazodone, and atypical antipsychotics is reviewed. Further, parents and caregivers should be provided with appropriate education on the nature of the sleep disorders and the expectation for modest pharmacologic benefit, at best. Additional data from well-designed trials in children with NDDs are desperately needed to gain a better understanding of sleep pharmacotherapy including efficacy and safety implications. Until then, clinicians must rely on the limited available data, as well as clinical expertise, when managing sleep disorders in the population of children with NDDs.

https://accpjournals.onlinelibrary.wiley.com/doi/pdf/10.1002/phar.1686

Management of Sleep Disorders in Children With Neurodevelopmental Disorders: A Review.

The mammalian diving response is a remarkable behavior that overrides basic homeostatic reflexes. It is most studied in large aquatic mammals but is seen in all vertebrates. Pelagic mammals have developed several physiological adaptations to conserve intrinsic oxygen stores, but the apnea, bradycardia, and vasoconstriction is shared with those terrestrial and is neurally mediated. The adaptations of aquatic mammals are reviewed here as well as the neural control of cardiorespiratory physiology during diving in rodents.

The Mammalian Diving Response: An Enigmatic Reflex to Preserve Life?

Central autonomic circuits in the brain and spinal cord are essential to vertebrate life: they control all basic bodily functions, including blood pressure, body temperature regulation, digestion, and reproduction. Edited by two experts in the field, Ida Llewellyn-Smith and Anthony Verberne, and extensively illustrated, the second edition of Central Regulation of Autonomic Functions presents the extraordinary advances that have been made over the last 20 years in the understanding of how the central nervous system controls autonomic functions. Written in a clear and readable manner by an international collection of neuroscientists and physiologists, and nine chapters describe central autonomic circuits from the cerebral cortex to the periphery. Eight more chapters address specific bodily functions and their control by central autonomic circuits. Two additional chapters discuss cardio-respiratory integration and regulation of autonomic function by visceral and somatic afferents. All of the chapters are up-to-date and cover topics such as the central autonomic regulation of airways, gastrointestinal function, energy homeostasis, body temperature, and sexual function, reflecting the latest research. One of the only texts to provide the whole story of how the brain controls basic bodily functions that are critical for life, Central Regulation of Autonomic Functions will be essential reading for graduate students and researchers in neuroscience, anatomy, pharmacology and physiology as well as a valuable reference work for established workers in the field.

Central regulation of autonomic functions

This review summarizes recent work on two basic processes of central nervous system (CNS) control of cholinergic outflow to the airways: 1) transmission of bronchoconstrictive signals from the airways to the airway-related vagal preganglionic neurons (AVPNs) and 2) regulation of AVPN responses to excitatory inputs by central GABAergic inhibitory pathways. In addition, the autocrine-paracrine modulation of AVPNs is briefly discussed. CNS influences on the tracheobronchopulmonary system are transmitted via AVPNs, whose discharge depends on the balance between excitatory and inhibitory impulses that they receive. Alterations in this equilibrium may lead to dramatic functional changes. Recent findings indicate that excitatory signals arising from bronchopulmonary afferents and/or the peripheral chemosensory system activate second-order neurons within the nucleus of the solitary tract (NTS), via a glutamate-AMPA signaling pathway. These neurons, using the same neurotransmitter-receptor unit, transmit information to the AVPNs, which in turn convey the central command to airway effector organs: smooth muscle, submucosal secretory glands, and the vasculature, through intramural ganglionic neurons. The strength and duration of reflex-induced bronchoconstriction is modulated by GABAergic-inhibitory inputs and autocrine-paracrine controlling mechanisms. Downregulation of GABAergic inhibitory influences may result in a shift from inhibitory to excitatory drive that may lead to increased excitability of AVPNs, heightened airway responsiveness, and sustained narrowing of the airways. Hence a better understanding of these normal and altered central neural circuits and mechanisms could potentially improve the design of therapeutic interventions and the treatment of airway obstructive diseases.

Brain stem excitatory and inhibitory signaling pathways regulating bronchoconstrictive responses.

In the cat, vagal postganglionic controls of heart rate, atrio-ventricular (AV) conduction and left ventricular contractility are mediated by three separate intrinsic cardiac ganglia, the sinoatrial (SA), AV and cranioventricular (CV) ganglia, respectively. The vagal preganglionic neurons (VPNs) that project to these ganglia are located in the ventrolateral nucleus ambiguus (NA-VL). We have previously shown that the VPNs projecting to the SA, AV and CV ganglia are distinct from one another. We have also demonstrated that neuropeptide Y-immunoreactive (NPY-IR) axon terminals synapse upon VPNs projecting to the SA ganglion. In the present study, we test the hypothesis that those VPNs projecting to the AV ganglion (negative dromotropic VPNs) and those projecting to the CV ganglion (negative inotropic VPNs) are innervated by NPY-IR terminals in NA-VL. A retrograde tracer was injected into the AV or CV ganglion of the cat, and the brains subsequently processed for visualization of tracer and the immunocytochemical visualization of NPY by dual labeling electron-microscopic methods. We observed that 11+/-5% of all axodendritic synapses and 8+/-6% of all axosomatic synapses upon negative inotropic VPNs were NPY-IR. Furthermore, 19+/-14% of all axodendritic synapses upon negative dromotropic VPNs were NPY-IR. A few NPY-IR axosomatic synapses upon negative dromotropic neurons were also observed. NPY-IR terminals in NA-VL occasionally formed axosomatic synapses with NPY-IR neurons and axoaxonic synapses with unlabeled terminals. These results suggest that central NPY afferents to the NA-VL modulate the vagal preganglionic control of AV conduction and left ventricular contractility.

Central control of atrio-ventricular conduction and left ventricular contractility in the cat heart: Synaptic interactions of vagal preganglionic neurons in the nucleus ambiguus with neuropeptide Y-immunoreactive nerve terminals.

Monoaminergic Modulation in the Brainstem: Implication for Airway Function

and airway resistance to vagal stimulation in piglets Endogenous nitric oxide modulates responses of tissue

cholinergic outflow to the airways A GABAergic inhibitory microcircuit controlling

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