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The Journal of Physiology Jun 2006Sympathetic nerves innervate the airways of most species but their reflex regulation has been essentially unstudied. Here we demonstrate sympathetic nerve-mediated... (Comparative Study)
Comparative Study
Sympathetic nerves innervate the airways of most species but their reflex regulation has been essentially unstudied. Here we demonstrate sympathetic nerve-mediated reflex relaxation of airway smooth muscle measured in situ in the guinea-pig trachea. Retrograde tracing, immunohistochemistry and electrophysiological analysis identified a population of substance P-containing capsaicin-sensitive spinal afferent neurones in the upper thoracic (T1-T4) dorsal root ganglia (DRG) that innervate the airways and lung. After bilateral vagotomy, atropine pretreatment and pre-contraction of the trachealis with histamine, nebulized capsaicin (10-60 microm) evoked a 63+/-7% reversal of the histamine-induced contraction of the trachealis. Either the beta-adrenoceptor antagonist propranolol (2 microm, administered directly to the trachea) or bilateral sympathetic nerve denervation of the trachea essentially abolished these reflexes (10+/-9% and 6+/-4% relaxations, respectively), suggesting that they were mediated primarily, if not exclusively, by sympathetic adrenergic nerve activation. Cutting the upper thoracic dorsal roots carrying the central processes of airway spinal afferents also markedly blocked the relaxations (9+/-5% relaxation). Comparable inhibitory effects were observed following intravenous pretreatment with neurokinin receptor antagonists (3+/-7% relaxations). These reflexes were not accompanied by consistent changes in heart rate or blood pressure. By contrast, stimulating the rostral cut ends of the cervical vagus nerves also evoked a sympathetic adrenergic nerve-mediated relaxation that were accompanied by marked alterations in blood pressure. The results indicate that the capsaicin-induced reflex-mediated relaxation of airway smooth muscle following vagotomy is mediated by sequential activation of tachykinin-containing spinal afferent and sympathetic efferent nerves innervating airways. This sympathetic nerve-mediated response may serve to oppose airway contraction induced by parasympathetic nerve activation in the airways.
Topics: Adrenergic Fibers; Animals; Capsaicin; Dose-Response Relationship, Drug; Guinea Pigs; Male; Muscle Relaxation; Muscle, Smooth; Neurons, Afferent; Reflex; Trachea
PubMed: 16581869
DOI: 10.1113/jphysiol.2005.104661 -
Muscle & Nerve Nov 2013Sensory neuronopathy (SNN) mimics distal sensory axonopathy. The conventional H-reflex elicited by tibial nerve stimulation (tibial H-reflex) is usually abnormal in both...
INTRODUCTION
Sensory neuronopathy (SNN) mimics distal sensory axonopathy. The conventional H-reflex elicited by tibial nerve stimulation (tibial H-reflex) is usually abnormal in both conditions. We evaluated the proximally evoked soleus H-reflex in response to S1 nerve root stimulation (S1 foramen H-reflex) in SNN.
METHODS
Eleven patients with SNN and 6 with distal sensory axonopathy were studied. Tibial and S1 foramen H-reflexes were performed bilaterally in each patient.
RESULTS
Tibial and S1 foramen H-reflexes were absent bilaterally in all patients with SNN. In the patients with distal sensory axonopathy, tibial H-reflexes were absent in 4 and demonstrated prolonged latencies in 2, but S1 foramen H-reflexes were normal.
CONCLUSIONS
Characteristic absence of the H-reflex after both proximal and distal stimulation reflects primary loss of dorsal root ganglion (DRG) neurons and the distinct non-length-dependent impairment of sensory nerve fibers in SNN.
Topics: Adult; Aged; Electric Stimulation; Electromyography; Female; Ganglia, Spinal; H-Reflex; Humans; Male; Middle Aged; Muscle, Skeletal; Peripheral Nervous System Diseases; Sensation Disorders; Sensory Receptor Cells; Spinal Nerve Roots; Tibial Nerve; Young Adult
PubMed: 23893555
DOI: 10.1002/mus.23975 -
Journal of Neurophysiology Jan 1956
Topics: Ganglia, Spinal; Reflex; Spinal Nerve Roots; Spinal Nerves
PubMed: 13286722
DOI: 10.1152/jn.1956.19.1.61 -
The International Journal of... Nov 2013Hoffmann reflex to tibial nerve stimulation at the popliteal fossa (tibial H-reflex) is routinely used to evaluate S1 radiculopathy. However, it lacks sensitivity... (Randomized Controlled Trial)
Randomized Controlled Trial
Hoffmann reflex to tibial nerve stimulation at the popliteal fossa (tibial H-reflex) is routinely used to evaluate S1 radiculopathy. However, it lacks sensitivity because other lesions along this reflex circuit affect the H-reflex bilaterally. This study was undertaken to determine whether the H-reflex evoked by stimulating proximally at the S1 foramen (S1 foramen H-reflex) could improve S1 root lesion evaluation sensitivity in patients with diabetes mellitus. A randomized paired study was designed to evaluate tibial and S1 foramen H-reflexes; bilateral H-M interval (HMI) and H-reflex latency were compared in 22 diabetic patients with unilateral S1 radiculopathy. Other electrophysiological evaluations included standard tibial conduction studies, sural conduction studies and needle electromyography (EMG). The S1 foramen H-reflex had a significantly higher sensitivity (91.0%, 20 of 22) in evaluating S1 radiculopathy than the conventional tibial H-reflex (63.6%, 14 of 22, p < 0.05). Bilateral tibial compound muscle action potential amplitudes were reduced in 3 patients, and sural sensory nerve action potential amplitudes decreased in 7 patients. Needle EMG revealed denervation restricted to the paraspinal muscle and myotomes supplied by the S1 nerve root on the ipsilateral side in 18 patients, and multiple lumbosacral nerve roots were involved bilaterally in the other 4 patients. Our results demonstrate that the S1 foramen H-reflex is a more sensitive assessment of S1 compressive radiculopathy in patients with diabetes mellitus.
Topics: Adult; Diabetes Mellitus; Electromyography; Female; H-Reflex; Humans; Male; Middle Aged; Radiculopathy; Sacrum; Spinal Nerve Roots
PubMed: 23724973
DOI: 10.3109/00207454.2013.801843 -
Journal of Neurophysiology Sep 2020Plastic adaptations are known to take place in muscles, tendons, joints, and the nervous system in response to changes in muscle activity. However, few studies have...
Plastic adaptations are known to take place in muscles, tendons, joints, and the nervous system in response to changes in muscle activity. However, few studies have addressed how these plastic adaptations are related. Thus this study focuses on changes in the mechanical properties of the ankle plantarflexor muscle-tendon unit, stretch reflex activity, and spinal neuronal pathways in relation to cast immobilization. The left rat hindlimb from toes to hip was immobilized with a plaster cast for 1, 2, 4, or 8 wk followed by acute electrophysiological recordings to investigate muscle stiffness and stretch reflex torque. Moreover, additional acute experiments were performed after 4 wk of immobilization to investigate changes in the central gain of the stretch reflex. Monosynaptic reflexes (MSR) were recorded from the L4 and L5 ventral roots following stimulation of the corresponding dorsal roots. Rats developed reduced range of movement in the ankle joint 2 wk after immobilization. This was accompanied by significant increases in the stiffness of the muscle-tendon complex as well as an arthrosis at the ankle joint at 4 and 8 wk following immobilization. Stretch reflexes were significantly reduced at 4-8 wk following immobilization. This was associated with increased central gain of the stretch reflex. These data show that numerous interrelated plastic changes occur in muscles, connective tissue, and the central nervous system in response to changes in muscle use. The findings provide an understanding of coordinated adaptations in multiple tissues and have important implications for prevention and treatment of the negative consequences of immobilization following injuries of the nervous and musculoskeletal systems. Immobilization leads to multiple simultaneous adaptive changes in muscle, connective tissue, and central nervous system.
Topics: Adaptation, Physiological; Animals; Ankle Joint; Atrophy; Immobilization; Male; Muscle, Skeletal; Range of Motion, Articular; Rats; Rats, Sprague-Dawley; Reflex, Monosynaptic; Reflex, Stretch; Spinal Nerve Roots
PubMed: 32783594
DOI: 10.1152/jn.00748.2019 -
American Journal of Physical Medicine &... 1996The pronator reflex has been used clinically and electrophysiologically to evaluate the sixth and seventh cervical roots (C-6, C-7). This has been proven to be the...
The pronator reflex has been used clinically and electrophysiologically to evaluate the sixth and seventh cervical roots (C-6, C-7). This has been proven to be the result of stretching the pronator teres muscle. We examined 25 healthy individuals with surface electromyogram to establish electrophysiologically the reproducibility and reliability of this reflex, in addition to finding the 95% confidence interval (C.I.) for the latency for both males and females and to correlate it with the arm length. Standard procedure was used for all people. To elicit the pronator teres reflex, the volar report of the distal radius was struck by the hammer with the forearm in neutral position and the elbow flexed at 90 degrees. The response was pronation of the forearm. A reproducible diphasic response was found in all individuals. The mean latency was 15.9 (+/-1.3) ms with the 95% C.I. 16.8 for females and 17.4 (+/- 1.4) ms with the 95% C.I. 18.7 for males. The data were collected to be used for further evaluation of C-6, C-7 radiculopathy.
Topics: Adult; Arm; Electrodes; Electromyography; Electrophysiology; Female; Humans; Male; Middle Aged; Pronation; Reference Values; Reflex; Reproducibility of Results
PubMed: 8873698
DOI: 10.1097/00002060-199609000-00003 -
Archives of Physical Medicine and... Aug 1976
Topics: H-Reflex; Humans; Nerve Compression Syndromes; Reflex, Monosynaptic; Spinal Nerve Roots
PubMed: 949240
DOI: No ID Found -
The Japanese Journal of Physiology 1985The nature of the afferent and efferent pathways of the recto-colonic reflex was studied electrophysiologically in the dog. A compound action potential consisting of...
The nature of the afferent and efferent pathways of the recto-colonic reflex was studied electrophysiologically in the dog. A compound action potential consisting of many peaks was evoked on a sacral dorsal rootlet by a stimulus to the ipsilateral rectal strands of the pelvic nerve. Conduction velocities of the peaks indicate that A delta and C afferent fibers innervate the colon and rectum. When the stimuli were subthreshold for C fibers, the reflex discharges of contralateral parasympathetic post-ganglionic fibers in the rectal strands and the reflex contraction of the colon were smaller than those caused by stronger stimuli. As the intensity of the stimulus to the sacral ventral roots was weakened, response peaks of preganglionic B fibers in the rectal branch, post-ganglionic C fibers in the rectal strands and a bladder branch of the pelvic nerve disappeared in the order of slow to fast conduction velocities. Contraction of the colon also decreased. The number of peaks arising from each nerve correlated well with the strength of the contraction. These results indicate that the peripheral limbs of the recto-colonic reflex arc consist of afferent A delta and C fibers, preganglionic B fibers and post-ganglionic C fibers.
Topics: Action Potentials; Afferent Pathways; Animals; Colon; Dogs; Efferent Pathways; Electric Conductivity; Electrophysiology; Muscle, Smooth; Rectum; Reflex; Urinary Bladder
PubMed: 4079135
DOI: 10.2170/jjphysiol.35.795 -
Current Protocols in Neuroscience Feb 2004Developmental tests are used to characterize early markers of behavior for investigation of the neurobiology of these behaviors, and to assess the impact of early...
Developmental tests are used to characterize early markers of behavior for investigation of the neurobiology of these behaviors, and to assess the impact of early prenatal or postnatal insult. These perturbations may include pharmacological, environmental, and genetic manipulations. At birth the rat is capable of some specific activities, but its movements are uncoordinated and seemingly random, its tactile sensitivity is not fully developed, and its ear canals and eyes remain closed until several days after birth. Postnatal development consists mainly of the continuation of processes begun earlier. This unit presents protocols for the most commonly used animal tests of developmental reflexology, including negative geotaxis, cliff avoidance, placing responses, tactile and acoustic startle responses, surface and air righting reflexes, crossed extensor reflex, rooting reflex, grasp reflex, bar holding, and horizontal and vertical screen tests.
Topics: Animals; Behavioral Sciences; Biomedical Research; Developmental Biology; Mice; Motor Activity; Neurobiology; Neurosciences; Rats; Reflex; Rodentia
PubMed: 18428605
DOI: 10.1002/0471142301.ns0818s25 -
Experimental Physiology Jun 2015What is the central question of this study? Nitrate supplementation via beetroot juice has been shown to have several benefits in healthy humans, including reduced blood... (Randomized Controlled Trial)
Randomized Controlled Trial
What is the central question of this study? Nitrate supplementation via beetroot juice has been shown to have several benefits in healthy humans, including reduced blood pressure and increased blood flow to exercising muscle. Whether nitrate supplementation can improve blood flow to the skin in heat-stressed humans has not been investigated. What is the main finding and its importance? Similar to previous studies, we found that nitrate supplementation reduces blood pressure. Nitrate supplementation increased vasodilatation in the skin of heat-stressed humans but did not directly increase skin blood flow. Nitrate supplementation has been shown to increase NO-dependent vasodilatation through both NO synthase (NOS)-dependent and NOS-independent pathways. We hypothesized that nitrate supplementation would augment reflex cutaneous active vasodilatation. Subjects were equipped with two microdialysis fibres on the forearm randomly assigned as control (Ringer solution) or NOS inhibition (20 mm l-NAME). Whole-body heating was performed to raise core temperature by 0.8°C above baseline core temperature. Maximal cutaneous vasodilatation was achieved via 54 mm sodium nitroprusside and local heating to 43°C. Skin blood flow (measured by laser-Doppler flowmetry) and blood pressure were measured. Cutaneous vascular conductance (CVC) was calculated as skin blood flow divided by mean arterial pressure (MAP) and expressed as a percentage of maximal CVC (%CVCmax ). Subjects underwent heat stress before and after nitrate supplementation (3 days of beetroot juice; 5 mm, 0.45 g nitrates per day). During heat stress, MAP was reduced following nitrate supplementation compared with the control conditions (before 88 ± 3 mmHg versus after 78 ± 2 mmHg; P < 0.05); however, resting MAP was not different between conditions (before 88 ± 3 mmHg versus after 83 ± 2 mmHg; P = 0.117). Nitrate supplementation increased plateau CVC at control sites (before 67 ± 2%CVCmax versus after 80 ± 5%CVCmax ; P = 0.01) but not at l-NAME-treated sites (before 45 ± 4%CVCmax versus after 40 ± 5%CVCmax ; P = 0.617). There was no change in the calculated percentage of NOS-dependent vasodilatation before and after supplementation (before 59 ± 4% versus after 64 ± 6%; P = 0.577). These data suggest that nitrate supplementation augments CVC and reduces MAP during heat stress.
Topics: Arterial Pressure; Beta vulgaris; Blood Flow Velocity; Blood Vessels; Body Temperature Regulation; Dietary Supplements; Enzyme Inhibitors; Female; Fruit and Vegetable Juices; Heart Rate; Heat Stress Disorders; Humans; Kansas; Laser-Doppler Flowmetry; Male; Microdialysis; NG-Nitroarginine Methyl Ester; Nitrates; Nitric Oxide Synthase; Plant Roots; Reflex; Regional Blood Flow; Skin; Time Factors; Vasodilation; Vasodilator Agents; Young Adult
PubMed: 25826741
DOI: 10.1113/EP085061