Dependence of Intracellular End-Plate Action Potential on Adjacent Fiber Activity

1956 ◽  
Vol 187 (1) ◽  
pp. 199-202 ◽  
Author(s):  
Dexter M. Easton
Keyword(s):  
Action Potential ◽  
Action Potentials ◽  
Rana Pipiens ◽  
End Plate ◽  
Lower Maximum ◽  
The Difference ◽  
Adductor Longus ◽  
Intracellular Action ◽  
Stimulation Of

Intracellular action potentials were recorded at the end plate and 1 mm away from it in small bundles of m. adductor longus of Rana pipiens during stimulation of the nerve. The end-plate spike reached a lower maximum and the repolarization was slower when compared with the spikes recorded 1 mm away. The difference was of the form expected from externally recorded impulses, and was much diminished when the number of fibers was reduced to two to three. It is suggested that asynchrony of the activity in adjacent fibers explains the lesser distortion of action potentials distant from the end plate.

Low-Voltage-Activated Calcium Current Does Not Regulate the Firing Behavior in Paired Mechanosensory Neurons With Different Adaptation Properties

2000 ◽  
Vol 83 (2) ◽  
pp. 746-753 ◽  
Author(s):  
Shin-Ichi Sekizawa ◽  
Andrew S. French ◽  
Päivi H. Torkkeli
Keyword(s):  
Action Potential ◽  
Action Potentials ◽  
Low Voltage ◽  
Firing Frequency ◽  
Oscillatory Behavior ◽  
Firing Behavior ◽  
Single Action ◽  
Synaptic Excitation ◽  
Intracellular Ca ◽  
The Difference

Low-voltage-activated Ca2+ currents (LVA- I Ca) are believed to perform several roles in neurons such as lowering the threshold for action potentials, promoting burst firing and oscillatory behavior, and enhancing synaptic excitation. They also may allow rapid increases in intracellular Ca2+ concentration. We discovered LVA- I Ca in both members of paired mechanoreceptor neurons in a spider, where one neuron adapts rapidly (Type A) and the other slowly (Type B) in response to a step stimulus. To learn if I Ca contributed to the difference in adaptation behavior, we studied the kinetics of I Ca from isolated somata under single-electrode voltage-clamp and tested its physiological function under current clamp. LVA- I Ca was large enough to fire single action potentials when all other voltage-activated currents were blocked, but we found no evidence that it regulated firing behavior. LVA- I Ca did not lower the action potential threshold or affect firing frequency. Previous experiments have failed to find Ca2+-activated K+ current ( I K(Ca)) in the somata of these neurons, so it is also unlikely that LVA- I Ca interacts with I K(Ca) to produce oscillatory behavior. We conclude that LVA-Ca2+ channels in the somata, and possible in the dendrites, of these neurons open in response to the depolarization caused by receptor current and by the voltage-activated Na+ current ( I Na) that produces action potential(s). However, the role of the increased intracellular Ca2+ concentration in neuronal function remains enigmatic.

scholarly journals Radial propagation of muscle action potential along the tubular system examined by potential-sensitive dyes.

1980 ◽  
Vol 76 (6) ◽  
pp. 751-762 ◽  
Author(s):  
S Nakajima ◽  
A Gilai
Keyword(s):  
Action Potential ◽  
Action Potentials ◽  
Time Course ◽  
Surface Membrane ◽  
Simultaneous Recording ◽  
Conduction Delay ◽  
Muscle Action Potential ◽  
Tubular System ◽  
Intracellular Action ◽  
T System

Isolated single (Xenopus) muscle fibers were stained with a non-permeant potential-probing dye, merocyanine rhodanine (WW375) or merocyanine oxazolone (NK2367). When the fiber was massively stimulated, an absorption change (wave a), which seemed to reflect the action potential, occurred. Simultaneous recording of optical changes and intracellular action potentials revealed that the time-course of wave a was slower than the action potential: the peak of wave a was attained at 1 ms, and the peak of action potential was reached at 0.5 ms after the stimulation. This difference suggests that wave a represents the potential changes of the whole tubular membrane and the surface membrane, whereas the action potential represents a surface potential change. This idea was substantiated by recording absorption signals preferentially from the surface membrane by recording the absorption changes at the edge of the fiber. Wave a obtained by this method was as quick as the intracellular action potential. The value of radial conduction velocity of action potential along the T system, calculated by comparing the action potential with wave a, was 6.4 cm/s at 24.5 degrees C, in fair agreement with González-Serratos (1971. J. Physiol. [Lond.]. 212:777-799). The shape of wave a suggests the existence of an access delay (a conduction delay at the orifice of the T system) of 130 microseconds.

scholarly journals Action potentials of isolated single muscle fibers recorded by potential-sensitive dyes.

1980 ◽  
Vol 76 (6) ◽  
pp. 729-750 ◽  
Author(s):  
S Nakajima ◽  
A Gilai
Keyword(s):  
Action Potentials ◽  
Light Transmission ◽  
Surface Membrane ◽  
Muscle Fibers ◽  
Single Muscle ◽  
Squid Axon ◽  
Vertebrate Muscle ◽  
Tubular System ◽  
The Difference ◽  
Stimulation Of

Light transmission changes upon massive stimulation of single muscle fibers of Xenopus were studied with the potential-sensitive nonpermeant dyes, merocyanine rhodanine (WW375) and merocyanine oxazolone (NK2367). Upon stimulation an absorption change (wave a) occurred, which probably represents the sum of action potentials in the transverse tubules and surface membrane. In WW375-stained fibers wave a is a decrease in transmission over the range of 630 to 730 nm (with NK2367, over the range of 590 to 700 nm) but becomes an increase outside this range, thus showing a triphasic spectral pattern. This spectrum differs from that of the squid axon, in which depolarization produces only an increase in transmission over the whole range of wavelengths (Ross et al. 1977. J. Membr. Biol. 33:141-183). When wave a was measured at the edge of the fiber to obtain more signal from the surface membrane, the spectrum did not seem to differ markedly from that obtained from the entire width of the fiber. Thus, the difference in the spectrum between the squid axon and the vertebrate muscle cannot be attributed to the presence of the tubular system.

scholarly journals The effect of evocalcet on vagus nerve activity of the gastrointestinal tract in miniature pigs

PLoS ONE ◽  
2021 ◽  
Vol 16 (1) ◽  
pp. e0245785
Author(s):  
Shin Tokunaga ◽  
Takehisa Kawata
Keyword(s):  
Vagus Nerve ◽  
Action Potentials ◽  
Vehicle Group ◽  
Gi Tract ◽  
Direct Stimulation ◽  
Miniature Pigs ◽  
Nerve Action ◽  
Calcimimetic Agents ◽  
The Difference ◽  
Stimulation Of

Evocalcet is a novel calcimimetic agent with fewer gastrointestinal (GI) adverse effects compared to cinacalcet. Although it is thought that cinacalcet induces GI side effects through the direct stimulation of the calcium receptor (CaR) expressed in the GI tract, the differences in the direct stimulatory effects of these two drugs on the GI tract have not been reported. In this study, we analyzed the difference in the GI effects of these two calcimimetic agents using miniature pigs by detecting vagus nerve stimulation after oral administration of the agents. Although cinacalcet induced vomiting in miniature pigs, evocalcet never induced emetic symptoms. A significant increase in the vagus nerve action potentials was observed after the administration of cinacalcet. Although the increase of that after the administration of evocalcet was mild and not significant in comparison to that in the vehicle group, it was not significantly different from the vagus nerve action potentials after cinacalcet treatment.

Interactions of area postrema and solitary tract in the nucleus tractus solitarius

1991 ◽  
Vol 260 (5) ◽  
pp. H1466-H1473 ◽  
Author(s):  
M. Hay ◽  
V. S. Bishop
Keyword(s):  
Action Potential ◽  
Neuronal Activity ◽  
Action Potentials ◽  
Nucleus Tractus Solitarius ◽  
Area Postrema ◽  
Rabbit Brain ◽  
Solitary Tract ◽  
Simultaneous Stimulation ◽  
Peripheral Afferents ◽  
Stimulation Of

The nucleus tractus solitarius (NTS) receives information from both area postrema (AP) and peripheral afferents. It is, therefore, one likely site of interaction between AP and peripheral afferent fibers. The present study's purpose was to determine the influence of AP stimulation on solitary tract-induced modulation of NTS neuronal activity. With the use of an in vitro rabbit brain slice preparation, extracellular recordings were made from 58 NTS neurons in which action potentials were evoked by both solitary tract and AP stimulation. In the majority of the cells tested, simultaneous stimulation of solitary tract and AP, at voltage levels that evoked no action potentials when stimulated separately, resulted in production of either single or multiple action potentials. In 27 units, stimulation levels to the solitary tract and to the AP were adjusted such that their respective separate stimulations produced an NTS action potential less than 30% of the time. When the two inputs were stimulated together, simultaneous stimulations produced an NTS action potential 100% of the time, suggesting a facilitatory interaction between the AP and the solitary tract on NTS neuronal activity. In nine cells, perfusion of the slice with clonidine induced a facilitation of solitary tract-evoked NTS response to a level similar to that seen during simultaneous stimulation of the solitary tract with the AP. Application of the alpha 2-adrenergic receptor antagonist yohimbine blocked the ability of both clonidine and AP to facilitate the solitary tract-evoked response. These results support a possible interaction between AP and peripheral afferents and suggest that AP stimulation facilitates effects of solitary tract activation at the level of the NTS.

New Advances in Single Fiber Electromyography

2014 ◽  
pp. 28-57
Author(s):  
Javier Rodriguez-Falces
Keyword(s):  
Action Potential ◽  
Simulation Model ◽  
Action Potentials ◽  
Single Fibre ◽  
Shape Features ◽  
Technical Aspects ◽  
Intracellular Action Potential ◽  
Mathematical Expressions ◽  
Intracellular Action ◽  
General Perspective

The aim of this chapter is to present a general perspective of SFEMG together with a description of the anatomical, physiological, and technical aspects that are involved in the recording of single fibre action potentials (SFAPs). First, a simulation model that relates analytically the intracellular action potential (IAP) and SFAP mathematical expressions is described. Second, the most recent findings regarding the shape features of human SFAPs are outlined. Third, a description of how different types of needle electrodes affect the characteristics of the recorded potential is detailed. Fourth, an explanation of the most important effects of filtering on the SFAP characteristics is provided. Finally, a description of the principles of jitter estimation together with the most important sources of errors is presented.

Components of the cardiac action potential

1962 ◽  
Vol 203 (2) ◽  
pp. 258-260 ◽  
Author(s):  
T. Hoshiko ◽  
Nick Sperelakis
Keyword(s):  
Action Potential ◽  
Slow Wave ◽  
Action Potentials ◽  
The Other ◽  
Cardiac Action Potential ◽  
Intercalated Disc ◽  
Ringer’S Solution ◽  
Current Pulses ◽  
Cardiac Action ◽  
Intracellular Action

Two components have been observed in the intracellular action potentials of frog ventricular strips under conditions of impaired transmission. The strips were bathed in Ca-free, Mg Ringer's solution and were subjected to passage of current pulses through their length. Under these conditions a "notch" gradually developed at the beginning of the plateau and separated the action potential into a spike and a slow wave. In any given cell, the notch was often more prominent when the conditioned strip was stimulated from one end than from the other. Occasionally a spike in isolation spontaneously alternated with a spike plus slow wave response. The slow waves were generally graded in duration and magnitude with stimulus intensity or duration. The results are discussed in terms of a possible junctional response at the intercalated disc.

Prolongation and shortening of action potentials by electrical shocks in frog ventricular muscle

1994 ◽  
Vol 266 (6) ◽  
pp. H2348-H2358 ◽  
Author(s):  
S. B. Knisley ◽  
W. M. Smith ◽  
R. E. Ideker
Keyword(s):  
Action Potential ◽  
Action Potentials ◽  
Maximum Rate ◽  
Transmembrane Potential ◽  
Ventricular Muscle ◽  
Intracellular Action Potential ◽  
Electrical Shocks ◽  
Intracellular Action ◽  
Maximum Rate Of Rise ◽  
Diastolic Potential

Effects of electrical shocks on myocardium are important for defibrillation. We measured effects of shocks (5 ms, 1–40 V/cm) in isolated frog ventricular strips. We recorded contraction strength and intracellular action potential (AP) with a shock-voltage cancellation technique to allow recordings immediately after shocks. Shocks of > or = 5 V/cm produced a dose- and latency-dependent prolongation of the AP ongoing during the shock. Stronger shocks of 28–40 V/cm decreased the duration, maximum diastolic potential, amplitude, and maximum rate of rise of the phase zero depolarization of paced APs that began after the shock. The contraction strength increased 43 and 59% during the 10 s after the stronger shocks. The transmembrane potential was shifted toward 0 mV immediately after the stronger shocks. We concluded that weak or strong shocks prolong the AP ongoing during the shock, whereas sufficiently strong shocks also shorten APs that begin after the shock. AP prolongation and shortening may be important for defibrillation and acceleration of tachycardia after failed cardioversion shocks.

scholarly journals VAGAL AND SYMPATHETIC EFFECTS ON THE PACEMAKER FIBERS IN THE SINUS VENOSUS OF THE HEART

1956 ◽  
Vol 39 (5) ◽  
pp. 715-733 ◽  
Author(s):  
Otto F. Hutter ◽  
Wolfgang Trautwein
Keyword(s):  
Membrane Potential ◽  
Action Potential ◽  
Action Potentials ◽  
Vagal Stimulation ◽  
Sinus Venosus ◽  
Sympathetic Stimulation ◽  
Pacemaker Potential ◽  
Pacemaker Potentials ◽  
Different Parts ◽  
Stimulation Of

1. Action potentials from sinus venosus and auricle fibers of spontaneously beating frog hearts have been recorded with intracellular electrodes. 2. Sinus fibers show a slow depolarization, the pacemaker potential, during diastole. The amplitude of this potential varies in different parts of the sinus. In some fibers the membrane potential falls by 11 to 15 mv. during diastole and the transition to the upstroke of the action potential is comparatively gradual. In other regions the depolarization develops more slowly and the action potential takes off more abruptly from a higher membrane potential. It is proposed that the fibers showing the largest fall in membrane potential during diastole are the pacemaker fibers of the heart, and that the rest of the preparation is excited by conduction. In auricle fibers the membrane potential is constant during diastole. 3. The maximum diastolic membrane potential and the overshoot of the action potential vary inversely with the amplitude of the pacemaker potential. The highest values were measured in auricle fibers. 4. Stimulation of vagi suppresses the pacemaker potentials. While the heart is arrested the membrane potential of the sinus fibers rises to a level above the maximum diastolic value reached in previous beats. In 28 experiments vagal stimulation increased the membrane potential from an average maximal diastolic value of 55 mv. to a "resting" level of 65.4 mv. The biggest vagal polarization was 23 mv. 5. In contrast to the sinus fibers vagal inhibition does not change the diastolic membrane potential of frog auricle fibers. 6. Vagal stimulation greatly accelerates the repolarization of the action potential and reduces its amplitude. These changes were seen both in the sinus and in auricle fibers stimulated by direct shocks during vagal arrest. 7. The conduction velocity in the sinus venosus of the tortoise is reduced by vagal stimulation. Block of conduction often occurs. 8. In the frog sinus venosus sympathetic stimulation increases the rate of rise of the pacemaker potential, accelerating the beat. The threshold remains unchanged. The rate of rise of the upstroke and the amplitude of the overshoot are increased. 9. The analogies between the vagal inhibition of the heart and the nervous inhibition of other preparations are discussed.

scholarly journals EXTRAGLANDULAR INNERVATION OF THE SALIVARY CELLS OF THE LEECH HAEMENTERIA GHILIANII: NEURONAL STIMULATION ELICITS GLAND-CELL ACTION POTENTIALS AND SECRETION

1989 ◽  
Vol 143 (1) ◽  
pp. 389-410
Author(s):  
WERNER A. WUTTKE ◽  
ROY T. SAWYER ◽  
MICHAEL S. BERRY
Keyword(s):  
Action Potential ◽  
Salivary Glands ◽  
Cell Body ◽  
Action Potentials ◽  
Gland Cell ◽  
Repetitive Firing ◽  
Gland Cells ◽  
Secretory Products ◽  
The Brain ◽  
Stimulation Of

1. Each salivary gland cell of Haementeria extends a single process, or ductule, anteriorly into the proboscis; secretory products are released at the ductule ending. Some ductules secrete into the lumen of the proboscis and others at the outer surface of its tip, more than 5 cm from the gland in large leeches 2. Depolarization of a gland-cell body elicits action potentials which appear to be conducted along the ductule to its ending. Electrical stimulation of the proboscis tip elicits action potentials in those ductules which end there, and the impulses are propagated to the cell body (approx. 5cms−1) 3. Bathing the salivary glands in calcium-free saline causes spontaneous repetitive firing in the cell bodies and also elicits secretion at the proboscis tip (bathed in normal saline); the action potential thus appears to be a stimulus for secretion 4. A paired stomatogastric nerve, from the brain, enters the proboscis near its base. Cobalt-filling of the nerve shows numerous cell bodies in the brain and first body ganglion, and an intricate network of fibres and a cluster of stained cell bodies near its entry point in the proboscis 5. Repetitive stimulation of the stomatogastric nerve produces action potentials in certain gland cells, after a delay of at least 15 s, and also elicits secretion. The action potentials are initiated near the ductule tip, and are conducted to the cell body. The salivary glands themselves do not appear to be innervated 6. Application of acetylcholine (ACh), dopamine or octopamine (10−4 moll−1) does not initiate secretion. Neither dopamine nor octopamine excites the gland cells but ACh produces a transient suprathreshold depolarization of the cell body and occasionally elicits 1–3 ductule spikes when applied to the proboscis tip. 5-Hydroxytryptamine (5-HT) produces secretion when applied to the proboscis but not when applied to the glands alone; it does not excite the cells, indicating that the action potential is not the only stimulus for secretion. 5-HT produces a depolarization, and increase in membrane resistance, in the cell body, and prevents the rapid adaptation of action potentials which occurs during maintained depolarization 7. Electrophoretic analysis shows that the protein compositions of secretions at the proboscis tip and in the lumen are completely different, with the tip apparently secreting only two major proteins. These same two protein bands occur in the cytoplasm of certain gland-cell bodies which can be distinguished in living glands on the basis of size and degree of staining with Methylene Blue 8. Following stimulation of the stomatogastric nerve, secretory products at the proboscis tip can be seen to emerge from discrete points which appear to be single ductule endings. This presents the possibility of studying excitation-secretion coupling in single cells

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