scholarly journals Unpaired Median Neurones in a Lepidopteran Larva (Antheraea Pernyi): II. Peripheral Effects and Pharmacology

1988 ◽  
Vol 136 (1) ◽  
pp. 333-350 ◽  
Author(s):  
S. J. H. BROOKES
Keyword(s):  
Electrical Activity ◽  
Action Potentials ◽  
Cell Activity ◽  
Muscular Activity ◽  
Motor Units ◽  
Muscle Fibres ◽  
Somatic Muscle ◽  
Antheraea Pernyi ◽  
Excitatory Junction Potentials ◽  
Median Cell

Two unpaired median cells (MC1 and MC2) had a temporal pattern of firing that correlated with phasic muscular activity in preparations of larval Antheraea pernyi, and previous work has indicated that the axons of median cells are associated with nerve trunks innervating blocks of muscle. In spite of this, action potentials in median cells were not found to have any one-for-one effects on either the tension or the electrical activity of somatic muscle fibres. However, bursts of action potentials in MC2 were shown to modulate both tension production and electrophysiological activity of a number of motor units. These effects consisted of an increase in twitch tension, a relaxation of basal resting tension, an increase in relaxation rate following contractions, a hyperpolarization of some muscle fibres and an increase in amplitude of excitatory junction potentials. The relative potency of these different effects varied between fast and slow muscles. All of these effects were mimicked by the application of octopamine and synephrine, and in higher concentrations by a number of other biogenic amines and adrenergic agonists. The possibility that the effects of median cell activity were mediated by the release of endogenous octopamine was supported by the observation that phentolamine (10−5mol l−1) blocked the effects of both MC2 impulses and the application of exogenous octopamine, whereas propanolol affected neither set of responses. This observation also indicated a pharmacological similarity with a number of other octopamine-sensitive insect tissue preparations. MC1 had similar effects to MC2 on the electrical activity of a number of muscles, suggesting that these two cells play a similar role. These observations provide strong evidence for the presence of an identifiable octopaminergic system of neurones, similar to the dorsal unpaired median (DUM) neurones that have been extensively studied in the locust.

THE R.C.A.M.C. ELECTROMYOGRAPH MARK III

1947 ◽  
Vol 25e (2) ◽  
pp. 100-110 ◽  
Author(s):  
Herbert H. Jasper ◽  
William O. Forde
Keyword(s):  
Electrical Activity ◽  
Motor Unit ◽  
Action Potentials ◽  
Low Voltage ◽  
Low Noise ◽  
Muscle Fibres ◽  
Single Muscle ◽  
Nerve Injuries ◽  
Wide Range ◽  
Loud Speaker

The R.C.A.M.C. Electromyograph Mark III is an apparatus developed under the auspices of the National Research Council of Canada during the war for the study of casualties with peripheral nerve injuries. It was used principally to study the electrical activity of muscles as a sensitive test of their nerve supply and general condition with regards to atrophy, etc. It is now being used not only in the diagnosis and to follow the recovery of nerve injuries, but for the study of muscle activity in various neuromuscular diseases, including poliomyelitis.The electromyograph consists of (a) a high gain, low noise level, wide range calibrated, balanced, push–pull pre-amplifier, with built-in calibrator, (b) a cathode ray oscilloscope unit with photographic attachment, and incorporating a nerve and muscle stimulator of variable intensity and duration, and (c) a mobile loud speaker cabinet including the speaker power amplifier, battery, and battery charger.Action potentials from single muscle fibres, or groups of fibres known as the motor unit, are picked up by means of a small finely pointed needle electrode, insulated except at the very tip, thrust through the skin into the muscle. A reference electrode is placed on the skin next to the point of insertion of the needle and a distant grounded electrode is placed on the subject to aid in the elimination of stray electrical interference. Action potentials are then amplified through four stages of condenser coupled amplification. They are then of sufficient magnitude to be clearly observed or photographed on the calibrated screen of the cathode ray oscilloscope, which makes possible accurate measurement of each potential wave, both in voltage and duration. The sound of the muscle action potentials may be simultaneously heard in the loud speaker. With training, diagnosis of muscle conditions may be greatly aided by certain characteristic sounds produced by different kinds of muscle activity.For example, a denervated muscle gives rise, from single muscle fibres, to continuous low voltage random 'spikes' that produce in the loud speaker a 'crackling' sound recognized as fibrillation. At rest the normal muscle is electrically silent. It gives rise during contraction to action potentials that are much higher and of longer duration. They produce in the loud speaker a knocking sound recognized as a motor unit discharge. During recovery from a nerve injury, and in certain degenerative conditions, the motor unit becomes poorly synchronized or disintegrated producing very complex wave forms that produce a distinctive 'chugging' sound.The electrical stimulator, which is synchronized with the trace of the oscilloscope, makes it possible to test the responsiveness of single muscles to different forms of electrical current as well as to record the electrical activity of a given muscle in response to stimulation of its motor nerve at a distance. By the use of the same equipment, the nerve impulse can also be followed in its course down the nerve fibre.

scholarly journals Potentiometric measurement of membrane action potentials in frog muscle fibres

1966 ◽  
Vol 183 (1) ◽  
pp. 152-166 ◽  
Author(s):  
B. Frankenhaeuser ◽  
B. D. Lindley ◽  
R. S. Smith
Keyword(s):  
Action Potentials ◽  
Frog Muscle ◽  
Muscle Fibres ◽  
Membrane Action ◽  
Potentiometric Measurement

scholarly journals Action potentials induce biomagnetic fields in carnivorous Venus flytrap plants

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Anne Fabricant ◽  
Geoffrey Z. Iwata ◽  
Sönke Scherzer ◽  
Lykourgos Bougas ◽  
Katharina Rolfs ◽  
...  
Keyword(s):  
Electrical Activity ◽  
Action Potentials ◽  
Plant Stress ◽  
Optically Pumped ◽  
Long Distance ◽  
Noninvasive Diagnostics ◽  
Venus Flytrap ◽  
Dionaea Muscipula ◽  
Cell Arrays ◽  
Electrical Signaling

AbstractUpon stimulation, plants elicit electrical signals that can travel within a cellular network analogous to the animal nervous system. It is well-known that in the human brain, voltage changes in certain regions result from concerted electrical activity which, in the form of action potentials (APs), travels within nerve-cell arrays. Electro- and magnetophysiological techniques like electroencephalography, magnetoencephalography, and magnetic resonance imaging are used to record this activity and to diagnose disorders. Here we demonstrate that APs in a multicellular plant system produce measurable magnetic fields. Using atomic optically pumped magnetometers, biomagnetism associated with electrical activity in the carnivorous Venus flytrap, Dionaea muscipula, was recorded. Action potentials were induced by heat stimulation and detected both electrically and magnetically. Furthermore, the thermal properties of ion channels underlying the AP were studied. Beyond proof of principle, our findings pave the way to understanding the molecular basis of biomagnetism in living plants. In the future, magnetometry may be used to study long-distance electrical signaling in a variety of plant species, and to develop noninvasive diagnostics of plant stress and disease.

Electrical activity and relative length changes of dog limb muscles as a function of speed and gait

1981 ◽  
Vol 94 (1) ◽  
pp. 15-42 ◽  
Author(s):  
G. E. Goslow ◽  
H. J. Seeherman ◽  
C. R. Taylor ◽  
M. N. McCutchin ◽  
N. C. Heglund
Keyword(s):  
Electrical Activity ◽  
Stance Phase ◽  
Biceps Brachii ◽  
Vastus Lateralis ◽  
Activity Patterns ◽  
Relative Length ◽  
Muscular Activity ◽  
Triceps Brachii ◽  
Limb Muscles ◽  
Length Changes

Electrical activity and length changes of 11 muscles of the fore- and hind- limbs of dogs walking, running, and galloping on a treadmill, were measured as a function of forward speed and gait. Our purpose was to find out whether the activity patterns of the major limb muscles were consistent with the two mechanisms proposed for storage and recovery of energy within a stride: a ‘pendulum-like’ mechanism during a walk, and a ‘spring-like’ mechanism during a run. In the stance phase of the walking dog, we found that the supraspinatus, long head of the triceps brachii, biceps brachii, vastus lateralis, and gastrocnemius underwent only minor length changes during a relatively long portion of their activity, Thus, a major part of their activity during the walk seems consistent with a role in stabilization of the joints as the dog ‘pole-vaulted’ over its limbs (and thereby conserved energy). In the stance phase of trotting and/or galloping dogs, we found that the supraspinatus, lateral head of the triceps, vastus lateralis, and gastrocnemius were active while being stretched prior to shortening (as would be required for elastic storage of energy), and that this type of activity increased with increasing speed. We also found muscular activity in the select limb flexors that was consistent with storage of kinetic energy at the end of the swing phase and recovery during the propulsive stroke. This activity pattern was apparent in the latissimus dorsi during a walk and trot, and in the biceps femoris during a trot and gallop. We conclude that, during locomotion, a significant fraction of the electrical activity of a number of limbs muscles occurs while they undergo little or no length change or are being stretched prior to shortening and that these types of activities occur in a manner that would enable the operation of pendulum-like and spring-like mechanisms for conserving energy within a stride. Therefore these forms of muscular activity, in addition to the more familiar activity associated with muscle shortening, should be considered to be important during locomotion.

Neural Patterns Associated with Ventilatory Movements in Dragonfly Larvae

1970 ◽  
Vol 52 (1) ◽  
pp. 167-175
Author(s):  
P. J. MILL
Keyword(s):  
Control System ◽  
Motor Activity ◽  
Action Potentials ◽  
Motor Units ◽  
The Other ◽  
Ventilatory Control ◽  
Expiratory Phase ◽  
Segmental Nerve ◽  
Ventral Muscle ◽  
Stimulation Of

1. Rhythmic bursts of motor activity associated with the expiratory phase of ventilation have been recorded from the second lateral segmental nerves of posterior abdominal ganglia in Aeshna and Anax larvae. 2. In Aeshna the rhythmic expiratory bursts contain one, or sometimes two, motor units; whereas in Anax there are almost invariably three units. In both animals only one unit is associated with action potentials in the respiratory dorso-ventral muscle. 3. Motor activity synchronized with the expiratory bursts in the second nerves has been recorded from the other lateral nerves and from the last unpaired nerve. In addition the fifth lateral nerves carry inspiratory bursts. 4. It has been confirmed that stimulation of a first segmental nerve can re-set the ventilatory rhythm by initiating an expiratory burst in the second nerves. The original frequency is immediately resumed on cessation of stimulation. 5. The nature of the ventilatory control system in dragonfly larvae is discussed in relation to other rhythmic systems in the arthropods.

Long-term observations of spontaneous electrical activity of the uterine smooth muscle

1959 ◽  
Vol 196 (2) ◽  
pp. 343-350 ◽  
Author(s):  
C. Y. Kao
Keyword(s):  
Smooth Muscle ◽  
Electrical Activity ◽  
Action Potentials ◽  
Local Conditions ◽  
Pregnant Uterus ◽  
Implanted Electrodes ◽  
Spontaneous Electrical Activity ◽  
Myometrial Cells ◽  
Uterine Smooth Muscle

The spontaneous electrical activity of uterine smooth muscle was rather variable when acute observations were made. Therefore, a series of chronic experiments was performed with implanted electrodes to monitor a group of myometrial cells under different physiological conditions for periods up to eight weeks. The results showed that consistent behavior of myometrial cells could be observed provided similar hormonal status was maintained. Action potentials were rare or absent in myometrium of oophorectomized animals but were caused to appear by estrogen. In the pregnant uterus, action potentials increased both in amplitude and frequency of discharge as parturition approached, reached a peak at that time, and then declined in the postpartum days. The results indicated that in estrogen treatment and in parturition activities of myometrial cells were more synchronous. There was suggestive evidence that there were central impulses initiating activity in the pregnant uterus, and that the responses of the myometrium were affected by the local conditions.

scholarly journals Dependence of Spontaneous Electrical Activity and Basal Prolactin Release on Nonselective Cation Channels in Pituitary Lactotrophs

2012 ◽  
pp. 267-275 ◽  
Author(s):  
M. KUČKA ◽  
K. KRETSCHMANNOVÁ ◽  
S. S. STOJILKOVIC ◽  
H. ZEMKOVÁ ◽  
M. TOMIĆ
Keyword(s):  
Electrical Activity ◽  
Action Potentials ◽  
Gh3 Cells ◽  
Cation Channels ◽  
Organic Cations ◽  
Trpc Channels ◽  
Pituitary Cells ◽  
Prolactin Release ◽  
Nonselective Cation Channels ◽  
Mrna Transcripts

All secretory anterior pituitary cells fire action potentials spontaneously and exhibit a high resting cation conductance, but the channels involved in the background permeability have not been identified. In cultured lactotrophs and immortalized GH3 cells, replacement of extracellular Na+ with large organic cations, but not blockade of voltage-gated Na+ influx, led to an instantaneous hyperpolarization of cell membranes that was associated with a cessation of spontaneous firing. When cells were clamped at –50 mV, which was close to the resting membrane potential in these cells, replacement of bath Na+ with organic cations resulted in an outward-like current, reflecting an inhibition of the inward holding membrane current and indicating loss of a background-depolarizing conductance. Quantitative RT-PCR analysis revealed the high expression of mRNA transcripts for TRPC1 and much lower expression of TRPC6 in both lactotrophs and GH3 cells. Very low expression of TRPC3, TRPC4, and TRPC5 mRNA transcripts were also present in pituitary but not GH3 cells. 2-APB and SKF-96365, relatively selective blockers of TRPC channels, inhibited electrical activity, Ca2+ influx and prolactin release in a concentration-dependent manner. Gd3+, a common Ca2+ channel blocker, and flufenamic acid, an inhibitor of non-selective cation channels, also inhibited electrical activity, Ca2+ influx and prolactin release. These results indicate that nonselective cation channels, presumably belonging to the TRPC family, contribute to the background depolarizing conductance and firing of action potentials with consequent contribution to Ca2+ influx and hormone release in lactotrophs and GH3 cells.

Address of the President Sir Alan Hodgkin, O. M. at the Anniversary Meeting, 30 November 1973

1974 ◽  
Vol 185 (1078) ◽  
Keyword(s):  
Surface Membrane ◽  
Muscular Activity ◽  
Nerve Impulse ◽  
Muscular Contraction ◽  
Single Fibre ◽  
Muscle Fibres ◽  
Constant Length ◽  
Axon Membrane ◽  
Ultrastructural Studies ◽  
Mathematical Skill

The Copley Medal is awarded to Professor A. F. Huxley, F. R. S. A. F. Huxley has made outstanding contributions to our knowledge of the nerve impulse and of the mechanism by which muscle fibres are caused to contract. Jointly with Hodgkin, he introduced the powerful method of intracellular recording from nerve cells and showed that during the propagation of an impulse the mem­brane potential reverses its sign, and does not simply fall towards zero as had been widely believed. This work - interrupted by the 1939-45 war, but later resumed - led to the proposal that the impulse arises from a transient influx of sodium ions through the axon membrane. The ‘ionic theory’ of nervous conduction was then established by a series of convincing experiments and calculations for which Huxley later shared the Nobel Prize. Huxley next turned his attention to the mechanism of muscular contraction. He equipped himself for this purpose by inventing a new type of interference microscope. In experiments on living isolated muscle fibres, Huxley showed that contraction is accompanied by a shortening of the isotropic band of each sarco­mere, while the remaining portion (the anisotropic band) retains approximately constant length. His findings complemented the important ultrastructural studies of H. E. Huxley and led them both to propose a ‘sliding filament’ mechanism as the basis of muscular motion. During further microscopic observations on the living muscle fibre, A. F. Huxley produced most striking evidence on the way in which an excitatory potential change of the surface membrane is communicated, through local tubular channels, to the interior of the fibre where it activates the contractile elements. In his most recent work, A. F. Huxley has continued to develop his single-fibre technique to resolve even finer details of the dynamic changes which occur during muscular activity. His work is characterized by a rare combination of profound theoretical insight, mathematical skill and superb technical mastery, all of which has enabled him to select problems of first-rate importance and to pursue them with outstanding success.

Memoirs: The Muscles of the Adult Honey-bee (Apis mellifera L.)

1928 ◽  
Vol s2-71 (284) ◽  
pp. 563-651
Author(s):  
GUY D. MORISON
Keyword(s):  
Apis Mellifera ◽  
Alimentary Canal ◽  
Muscular Activity ◽  
Reproductive Organs ◽  
Muscle Fibres ◽  
Muscle Attachment ◽  
Apparent Lack ◽  
Histological Appearance ◽  
The Individual ◽  
Alary Muscles

1. The entire musculature of the alimentary canal is described in gross and in histological detail. The development of the muscle is considered. The innervation is described, likewise the tracheation and its relation to muscular activity and the bloodstream. 2. The heart is described with a detailed histological account of its muscle-fibres. Its tracheation is described and its apparent lack of innervation is discussed. 3. The ‘alary’ muscles of the dorsal diaphragm are described with a detailed account of their histology, innervation, and tracheation. 4. The ventral diaphragm is described as well as the histology, innervation, and tracheation of its muscle-fibres. The course of blood and physiological questions connected with it receive discussion. 5. The muscles of the reproductive organs of drone, queen, and worker are described with particular reference to the histology, innervation, tracheation, and physiology of their fibres. 6. The indirect muscles of the wings (fibrous muscle) have their histology, innervation, and tracheation described in detail. The method of contraction of the entire muscles and of the individual fibres and fibrils is discussed. The sarcosomes are described with their physiological significance to contraction. 7. The attachment of all the types of muscle found in the bee is described in histological detail. Different opinions of muscle attachment to chitin are summarized. 8. Throughout the paper, histological measurements are given for the various types of muscle-fibres and their nuclei in the three castes of bee. Since in the three castes the histological appearance is so similar for each type of muscle, the illustrations have been limited to portions of the muscles of worker bees.

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