The Paradox of Mytilus Muscle. A New Interpretation

1956 ◽  
Vol 33 (2) ◽  
pp. 295-310
Author(s):  
G. HOYLE ◽  
J. LOWY
Keyword(s):  
Electrical Stimulation ◽  
Electrical Activity ◽  
Smooth Muscles ◽  
Strong Support ◽  
Tonic Contraction ◽  
Mechanical Activity ◽  
Retractor Muscle ◽  
Pharmacological Interest ◽  
New Interpretation ◽  
Contraction And Relaxation

1. The mechanism of contraction and relaxation in the anterior byssus retractor muscle (A.B.R.M.) of the lamellibranch mollusc Mytilus edulis has been studied with refined stimulating and recording techniques. Two distinct types of response are present: phasic and tonic. The former can be evoked by all kinds of electrical stimulation, but the latter is most readily elicited by continuous direct current. 2. Serotonin (5-hydroxytryptamine) rapidly abolishes the tonic response, whilst leaving the phasic response practically unaffected for many hours. On electrical stimulation, a serotonin-treated muscle may show spontaneous electrical and mechanical activity, usually of a rhythmical nature. As the muscle is unable to destroy this drug the effects produced by it are likely to be of pharmacological interest only. 3. Electrical activity in the form of irregular volleys of muscle action potentials can be recorded from the intact A.B.R.M. and even after the nerves to the muscle have been cut. In such (externally) denervated preparations the spontaneous electrical activity is almost unaffected by a.c. stimulation but greatly increased by d.c. stimulation which evokes prolonged tonic contraction. 4. Stimulation of inhibitory nerves within the muscle quickly terminates a state of tonic contraction and at the same time reduces the electrical activity considerably. 5. An explanation is offered for the occurrence of electrical activity during relaxation of lamellibranch smooth muscles. The normal functioning of the A.B.R.M.is interpreted, and strong support is given to the tetanus hypothesis of tonic contraction.

Intracellular calcium translocation during contraction in vertebrate and invertebrate smooth muscles as studied by the pyroantimonate method

1982 ◽  
Vol 60 (4) ◽  
pp. 576-587 ◽  
Author(s):  
Haruo Sugi ◽  
Suechika Suzuki ◽  
Tateo Daimon
Keyword(s):  
Smooth Muscle ◽  
Plasma Membrane ◽  
Coronary Artery ◽  
Intracellular Localization ◽  
Muscle Fibers ◽  
Smooth Muscles ◽  
Electron Microscopic Examination ◽  
Mechanical Activity ◽  
Retractor Muscle ◽  
Electron Microscopic

The intracellular localization of activator Ca and its translocation during the mechanical activity were studied on vertebrate and invertebrate smooth muscles by fixing muscle fibers with a 1% OsO4 solution containing 2% potassium pyroantimonate for electron microscopic examination. When guinea-pig tacnia coli, Mytilus anterior byssal retractor muscle, and Dorabella longitudinal body wall muscle were fixed during the relaxed state, electron-opaque pyroantimonate precipitate containing Ca was localized along the inner surface of the plasma membrane and at other membranous structures in close apposition to the plasma membrane, in accordance with physiological evidence that these muscles contain intracellularly stored activator Ca. When they were fixed during the contracted state, the precipitate was distributed diffusely in the myoplasm in the form of small particles, indicating the release of activator Ca from the peripheral structures. The contraction in dog coronary artery smooth muscle appears to be associated with the inward movement of extracellular Ca. In accordance with this, the resting coronary artery muscle fibers exhibited the precipitate in the lumen of the caveolae, i.e., the bottle-shaped plasma membrane invaginations, but not at the peripheral intracellular structures, though the contracted fibers showed the diffuse distribution of the precipitate in the myoplasm. These results indicate that the pyroantimonate method is very effective in studying the translocation of activator Ca in various types of smooth muscle.

Transducer for recording electrical and mechanical chronic intestinal activity

1976 ◽  
Vol 41 (6) ◽  
pp. 942-945 ◽  
Author(s):  
A. Lambert ◽  
R. Eloy ◽  
J. F. Grenier
Keyword(s):  
Electrical Activity ◽  
Wheatstone Bridge ◽  
Displacement Transducer ◽  
Intestinal Wall ◽  
Mechanical Activity ◽  
Strain Gauges ◽  
Mechanical Displacement ◽  
Electrical Potentials ◽  
Intestinal Activity ◽  
Long Duration

An extraluminal displacement transducer has been developed for simultaneously recording the mechanical activity in two perpendicular directions andthe electrical activity of the intestinal serosa. The length variations in two perpendicular directions were measured by means of strain gauges bounded on two pairs of lamellae embedded in a rigid stand. The electrical activity was recorded by means of four electrodes situated at the extremity of these lamellae. The electrical gauges of each pair of lamellae are connected to form a Wheatstone bridge. This device allows establishment of a correlation between the mechanical displacement of the intestinal wall serosa and electrical potentials by means of studies of long duration.

scholarly journals Identification of serotonergic (5HT1A-type) receptors in broiler small intestine by application of serotonin and its agonists and antagonists

2011 ◽  
Vol 65 (1-2) ◽  
pp. 51-59 ◽  
Author(s):  
Indira Mujezinovic ◽  
Vitomir Cupic ◽  
Ahmed Smajlovic ◽  
Mehmed Muminovic
Keyword(s):  
Smooth Muscle ◽  
Small Intestine ◽  
Smooth Muscles ◽  
Muscle Layer ◽  
Force Transducer ◽  
Mechanical Activity ◽  
Organ Bath ◽  
Pathological Conditions ◽  
Isolated Organ Bath ◽  
Longitudinal Layer

Serotonin or 5-hydroxytryptamine (5-HT), is a monoamine neurotransmitter synthesised from L-tryptophan in serotonergic neurons and enterochromaffin cells of the gastrointestinal tract. This neurotransmitter is widely distributed in the animal and plant kingdom and regulates some central and peripheral functions through several types of specific serotonergic (5-HT) receptors. Since it is known that the effect of serotonin, especially in pathological conditions, is very important, we believe that determining the types of receptors for this substance would make it possible to use their agonist or antagonists, which would undoubtedly enhance the pharmacotherapy of functional disruption of the small intestine in broilers. Investigations were carried out on isolated smooth muscle strips of the circular and longitudinal layer of the broiler small intestine (strip dimension 3-4 mm x 2 cm). The muscle strips were placed in an isolated organ bath. The mechanical activity of the preparations was recorded via an isotonic force transducer coupled to a pen recorder. This was done following the addition of serotonin (nonselective 5-HT agonist), 8-OH-DPAT (selective 5-HT1A agonist) and spiroxatrin (selective 5-HT1A antagonist). The sensitivity of the tissues to acetylcholine was tested before starting the experiments. Using the obtained results, it can be concluded that 5HT1A type receptors are present in smooth muscles of the broiler small intestine, duodenum and ileum, especially in the longitudinal smooth muscle layer which reacted with contractions even to low serotonin concentration (10-6), but not in the jejunum.

scholarly journals Co-Ordination of Pedal-Disk Detachment in the Sea Anemone Calliactis Parasitica

1969 ◽  
Vol 51 (2) ◽  
pp. 387-396
Author(s):  
I. D. MCFARLANE
Keyword(s):  
Electrical Stimulation ◽  
Electrical Activity ◽  
Mechanical Stimulation ◽  
Average Frequency ◽  
Conduction System ◽  
Identical Stimulus ◽  
Slow Conduction ◽  
Calliactis Parasitica ◽  
Behavioural Sequence ◽  
Stimulation Of

1. Electrical activity has been recorded from the sphincter region of Calliactis parasitica during the behavioural sequence in which the anemone detaches from the substrate and attaches to a Buccinum shell. The ectodermal slow-conduction system (SS1) fires repetitively, the majority of observed pulses occurring in the period prior to detachment (a typical example is 25 SS1pulses at an average frequency of 1 pulse/7 sec.). Shell-tentacle contact is essential for stimulation of SS1activity. 2. Mechanical stimulation of the column excites the SS1, and 30 stimuli at a frequency of about one shock/5 sec. give pedal disk detachment. 3. Electrical stimulation of the ectoderm excites the SS1and about 30 stimuli at frequencies between one shock/3 sec. and one shock/9 sec. produce detachment. Detachment and the SS1 have an identical stimulus threshold. It is concluded that detachment is co-ordinated by the SS1.

scholarly journals A new interpretation of thalamocortical circuitry

2002 ◽  
Vol 357 (1428) ◽  
pp. 1767-1779 ◽  
Author(s):  
Paul Adams ◽  
Kingsley Cox
Keyword(s):  
Simple Model ◽  
Electrical Activity ◽  
Neural Activity ◽  
New Interpretation ◽  
Almost All

Almost all the information that is needed to specify thalamocortical and neocortical wiring derives from patterned electrical activity induced by the environment. Wiring accuracy must be limited by the anatomical specificity of the cascade of events triggered by neural activity and culminating in synaptogenesis. We present a simple model of learning in the presence of plasticity errors. One way to achieve learning specificity is to build better synapses. We discuss an alternative, circuit–based, approach that only allows plasticity at connections that support highly selective correlations. This circuit resembles some of the more puzzling aspects of thalamocorticothalamic circuitry.

Electrical Activity in the Hydroid Cordylophora

1968 ◽  
Vol 49 (2) ◽  
pp. 387-400
Author(s):  
G. O. MACKIE
Keyword(s):  
Electrical Stimulation ◽  
Electrical Activity ◽  
Pulse Time ◽  
Apparent Effect ◽  
Muscle Response ◽  
Composite Event ◽  
Slow Pulse

1. Cordylophora has two major hydranth pacemaker systems, one producing slow,, biphasic pulses at 2.0-4.0 sec. intervals (slow pulse or SP system) and one exhibiting sharp, predominantly negative potentials singly or in bursts with a normal interval of 1.5-2.0 sec. between pulses (fast pulses, FPs). 2. Both SPs and FPs are recorded throughout the hydranth, but do not spread to and are not co-ordinated in adjacent hydranths. 3. SPs could not consistently be evoked artificially and showed no clear behavioural correlates. FPs occur during feeding and following electrical stimulation, where they may accompany a muscle response. 4. FPs appear superimposed on SPs when both systems are active. Such a composite event advances the SP rhythm by an amount close to the normal FP inter-pulse time, but compensatory adjustment of the SP rhythm then occurs. 5. Treatment with 10-5 g./ml. tetrodotoxin has no apparent effect on Cordylophora.

Abstract 294: A Machine Learning Approach in Using Capnography to Predict Resuscitation Interventions Required in Hypoxic Pseudo-Pulseless Electrical Activity Resuscitation

Circulation ◽  
2020 ◽  
Vol 142 (Suppl_4) ◽  
Author(s):  
Alexander L Lindqwister ◽  
Alexander Ivanov ◽  
Yiyuan D Hu ◽  
Samuel B Klein ◽  
Karen L Moodie ◽  
...  
Keyword(s):  
Machine Learning ◽  
Electrical Activity ◽  
Pulseless Electrical Activity ◽  
Roc Curves ◽  
Aortic Pressure ◽  
Machine Learning Algorithms ◽  
Mechanical Activity ◽  
Gradient Boosting ◽  
Maximum Slope ◽  
End Tidal

Introduction: Pseudo-Pulseless Electrical Activity (p-PEA) is a lifeless form of profound cardiac shock characterized by measurable cardiac mechanical activity without clinically detectable pulses. Patients in pseudo-PEA carry different prognoses than those in true PEA and may require different therapies. End-tidal carbon dioxide (ET-CO 2 ) has been studied in ventricular fibrillation and true PEA, but not in p-PEA. We evaluated the ability of capnography to predict the need for CPR in p-PEA. Methods: Female swine (N = 14) under intravenous anesthesia were instrumented with aortic and central venous micromanometer pressure catheters. ECG and ET-CO 2 were measured continuously. p-PEA was induced by ventilation with 6% oxygen in 94% nitrogen and was defined as a systolic aortic pressure less than 40 mmHg. Pigs were grouped into cohorts based on the interventions required to achieve ROSC: 100% O 2 , 100% O 2 + CPR, 100% O 2 + CPR + epinephrine. One hundred 4 sec. snippets of ET-CO 2 data were randomly sampled during the p-PEA state, and the mean, maximum, slope, and r-value of each epoch was used to train 7 machine learning algorithms to predict which intervention cohort they belonged to. Data was split randomly into 60% training and 40% testing sets. Results: Ensemble approaches were highly successful, with the gradient boosting model achieving an AUC of 0.91 on ROC curves (Figure 1), with an accuracy 0.83, sensitivity 0.86, specificity 0.78. Conclusions: In porcine hypoxic p-PEA, machine learning derived models of ET-CO2 appeared able to predict the degree of interventions needed for ROSC. If confirmed clinically, such an approach may be useful in guiding treatment of this increasingly common type of cardiac arrest.

Effect of tetraethylammonium on tonic airway smooth muscle: initiation of phasic electrical activity

1975 ◽  
Vol 228 (2) ◽  
pp. 633-636 ◽  
Author(s):  
EA Kroeger ◽  
NL Stephens
Keyword(s):  
Mechanical Properties ◽  
Smooth Muscle ◽  
Electrical Activity ◽  
Action Potentials ◽  
Membrane Conductance ◽  
Mechanical Activity ◽  
Myogenic Response ◽  
Intracellular Recordings ◽  
External Stimulation ◽  
Length Constant

We have previously shown that in the presence of tetraethylammonium (TEA, 6.7-67 mM) phasic mechanical activity and a myogenic response (MR) to quick stretch are produced in normally multi-unit tracheal smooth muscle. The present studies were designed to investigate the electrophysiological basis for these changes in the mechanical properties of the muscle. Intracellular recordings showed that in the presence of TEA the membrane was partially depolarized and trains of small (8-20 mV), decrementally conducted action potentials were produced spontaneously at a frequency of 15-20/min. Action potentials could also be stimulated by external electrodes, and the conduction velocity over short distances was 0.84 plus or minus 0.2 cm/s. Membrane conductance and rectification, as measured by the magnitude of electrotonic potentials in response to external stimulation, were reduced in the presence of TEA. The length constant was increased from 1.6 plus or minus 0.1 to 2.8 plus or minus 0.2 mm. These results are consistent with the notion that TEA produces phasic membrane electrical activity by reducing P-K.

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