scholarly journals Electrophysiology of Syncytial Smooth Muscle

2019 ◽  
Vol 13 ◽  
pp. 117906951882191 ◽  
Author(s):  
Rohit Manchanda ◽  
Shailesh Appukuttan ◽  
Mithun Padmakumar
Keyword(s):  
Smooth Muscle ◽  
Action Potentials ◽  
Signal Analysis ◽  
Computational Models ◽  
Vas Deferens ◽  
Contractile Activity ◽  
Smooth Muscles ◽  
Biophysical Analysis ◽  
Recent Developments ◽  
The Many

As in other excitable tissues, two classes of electrical signals are of fundamental importance to the functioning of smooth muscles: junction potentials, which arise from neurotransmission and represent the initiation of excitation (or in some instances inhibition) of the tissue, and spikes or action potentials, which represent the accomplishment of excitation and lead on to contractile activity. Unlike the case in skeletal muscle and in neurons, junction potentials and spikes in smooth muscle have been poorly understood in relation to the electrical properties of the tissue and in terms of their spatiotemporal spread within it. This owes principally to the experimental difficulties involved in making precise electrical recordings from smooth muscles and also to two inherent features of this class of muscle, ie, the syncytial organization of its cells and the distributed innervation they receive, which renders their biophysical analysis problematic. In this review, we outline the development of hypotheses and knowledge on junction potentials and spikes in syncytial smooth muscle, showing how our concepts have frequently undergone radical changes and how recent developments hold promise in unraveling some of the many puzzles that remain. We focus especially on computational models and signal analysis approaches. We take as illustrative examples the smooth muscles of two organs with distinct functional characteristics, the vas deferens and urinary bladder, while also touching on features of electrical functioning in the smooth muscles of other organs.

Effect of NO donors on protein phosphorylation in intact vascular and nonvascular smooth muscles

2001 ◽  
Vol 280 (4) ◽  
pp. H1565-H1580 ◽  
Author(s):  
James K. Hennan ◽  
Jack Diamond
Keyword(s):  
Smooth Muscle ◽  
Protein Kinase ◽  
Protein Phosphorylation ◽  
Vas Deferens ◽  
Smooth Muscles ◽  
Rat Aorta ◽  
Rat Vas Deferens ◽  
Two Dimensional Gel Electrophoresis ◽  
Relaxant Response ◽  
Underlying Mechanisms

It is generally well accepted that nitrovasodilator-induced relaxation of vascular smooth muscle involves elevation of cGMP and activation of a specific cGMP-dependent protein kinase [protein kinase G (PKG)]. However, the protein targets of PKG and the underlying mechanisms by which this kinase leads to a relaxant response have not been elucidated. Several types of smooth muscle, including rat myometrium and vas deferens, are not relaxed by sodium nitroprusside, even at concentrations that produce marked elevation of cGMP and activation of PKG. The main objective of our studies was to compare PKG-mediated protein phosphorylation in intact rat aorta, rat myometrium, and rat vas deferens using two-dimensional gel electrophoresis. In intact rat aorta, seven PKG substrates were detected during relaxation of the tissue. None of the PKG substrates identified in the rat aorta appeared to be phosphorylated in the myometrium or vas deferens after administration of various cGMP-elevating agents. Thus the failure of the rat myometrium and rat vas deferens to relax in the face of cGMP elevation and PKG activation may be due to a lack of PKG substrate phosphorylation.

Protein phosphorylation in cardiac and vascular smooth muscle

1981 ◽  
Vol 241 (2) ◽  
pp. H117-H128 ◽  
Author(s):  
M. Barany ◽  
K. Barany
Keyword(s):  
Smooth Muscle ◽  
Protein Phosphorylation ◽  
Light Chain ◽  
Myosin Light Chain ◽  
Current Knowledge ◽  
Smooth Muscles ◽  
Arterial Smooth Muscle ◽  
Cardiac Sarcoplasmic Reticulum ◽  
The Many ◽  
Contraction Cycle

In the heart and arterial smooth muscles, several proteins are phosphorylated. This review summarizes our current knowledge about these phosphoproteins and their possible role in the function of these muscles. In the contractile apparatus, the phosphorylation of myosin light chain seems to be an integral part of the contraction cycle of arterial smooth muscle. However, in the heart the relationship between light chain phosphorylation-dehosphorylation and systolic-diastolic states remains open. In the heart, the phosphorylation of the inhibitory subunit of troponin, a myofibrillar protein, parallels the positive inotropic response induced by beta-adrenergic agonists. It seems likely that this phosphorylation is involved in the physiological stimulation of the heart by epinephrine. Cardiac sarcoplasmic reticulum contains a low-molecular-weight protein, phospholamban, the phosphorylation of which is required for Ca2+ transport. Ion fluxes through the heart sarcolemma may also be controlled through membrane protein phosphorylation. Key enzymes of the energy-yielding pathways in the heart, the pyruvate dehydrogenase multienzyme complex and phosphorylase, are turned on and off by phosphorylation-dephosphorylation mechanisms. Our understanding of protein phosphorylation in the heart has advanced greatly. In contrast, with the exception of the myosin light chain, much less is known about the many proteins phosphorylated in arterial smooth muscle.

Tetrodotoxin-sensitive action potentials in smooth muscle of mouse vas deferens

1995 ◽  
Vol 52 (2-3) ◽  
pp. 237-240 ◽  
Author(s):  
Mollie E. Holman ◽  
Mary Anne Tonta ◽  
Helena C. Parkington ◽  
Harold A. Coleman
Keyword(s):  
Smooth Muscle ◽  
Action Potentials ◽  
Vas Deferens ◽  
Mouse Vas Deferens

scholarly journals Features of the bradykinin-induced contraction of the gastric smooth muscle depending on the concentration of compounds based on 3-substituted-1,4-benzodiazepin-2-ones

2016 ◽  
Vol 21 (2) ◽  
pp. 19-23
Author(s):  
P. Virych ◽  
O. Shelyuk ◽  
V. Martynyuk ◽  
V. Pavlovsky
Keyword(s):  
Smooth Muscle ◽  
Muscle Contraction ◽  
Contractile Activity ◽  
Smooth Muscles ◽  
Competitive Inhibitor ◽  
Smooth Muscle Contraction ◽  
Gastric Smooth Muscle ◽  
Low Concentrations

The effect of compounds based on 3-substituted-1,4-benzodiazepine-2-ones on contractile activity of smooth muscles of the rat's stomach was analyzed. Action substances MX-1626, MX-1775 for the smooth muscle contraction of like competitive inhibitor of bradykinin – des-Arg9- [Leu8]-Bradykinin acetate, which is observed as increase normalized rate of contraction with increasing of bradykinin concentration and characterized by a slowdown in the first phase of contraction. The most effective 3-subtituted 1,4-benzodiazepin-2-ones was at low concentrations of bradykinin, increasing it concentration their effect is reduced.

scholarly journals Hydrogen peroxide influence on contractile activity smooth muscle cells: the role of cytoskeleton

2009 ◽  
Vol 8 (4) ◽  
pp. 41-46
Author(s):  
I. V. Kovalyev ◽  
S. V. Gusakova ◽  
O. S. Melnik ◽  
M. B. Baskakov ◽  
L. V. Kapilevich ◽  
...  
Keyword(s):  
Hydrogen Peroxide ◽  
Smooth Muscle ◽  
Smooth Muscle Cells ◽  
Contractile Activity ◽  
Smooth Muscles ◽  
Potassium Conductance ◽  
Muscle Cells ◽  
Rat Aorta ◽  
Mechanisms Of Action

The influence of of hydrogen peroxide on the contractile reactions of smooth muscle cells caused by hyperpotassium solution end phenylephrine in modulation a potassium conductance the membrane and the state of cytoskeleton elements has been investigated by the mechanographical method. It has multidirectional influence of hydrogen peroxide in the reduction of smooth muscles of rat aorta with the membrane depolarization hyperpotassium solution and action phenylephrine: phenylephrine decline in value and increase strength hyperpotassium contractures. We show that the cytoskeleton components involved in the mechanisms of action of hydrogen peroxide in the contractile reactions of smooth muscles of rat aorta caused by phenylephrine.

scholarly journals Effects of Ursolic Acid on Contractile Activity of Gastric Smooth Muscles

2015 ◽  
Vol 10 (4) ◽  
pp. 1934578X1501000 ◽  
Author(s):  
Natalia Prissadova ◽  
Petko Bozov ◽  
Kiril Marinkov ◽  
Hristo Badakov ◽  
Atanas Kristev
Keyword(s):  
Smooth Muscle ◽  
Membrane Potential ◽  
Ursolic Acid ◽  
Slow Wave ◽  
Contractile Activity ◽  
Smooth Muscles ◽  
Dependent Manner ◽  
Krebs Solution ◽  
Concentration Dependent Manner ◽  
Gastric Smooth Muscle

Ursolic acid (UA) in concentrations of 1×10−7 mol/L - 5×10−5 mol/L induced relaxation in gastric smooth muscle (SM) tissues, in a concentration-dependent manner. The relaxation did not change membrane potential and slow wave contraction patterns. A significant decrease in amplitude and frequency of spike-potentials was observed. UA-induced reactivity was removed when SM preparations were treated with nifedipine (1×10−6 mol/L). Ca2+- induced contractions of the depolarized SM preparations (42 mmol/L K+; Ca2+- free Krebs solution) were substantially reduced in the presence of UA. It was determined that, in certain concentrations, UA influenced L – type Ca2+ channels, and reduced the Ca2+ influx.

THE ELECTRICAL PROPERTIES OF THE SMOOTH MUSCLE CELL MEMBRANE

1958 ◽  
Vol 36 (9) ◽  
pp. 959-975 ◽  
Author(s):  
E. E. Daniel ◽  
H. Singh
Keyword(s):  
Smooth Muscle ◽  
Electrical Properties ◽  
Action Potential ◽  
Action Potentials ◽  
Maximum Rate ◽  
Sodium Current ◽  
Choline Chloride ◽  
Total Duration ◽  
Smooth Muscles ◽  
Sodium Concentration

In myometrium from pregnant cat, repetitive action potentials have been recorded during contraction. Using intracellular electrodes the depolarizations averaged 35 mv. Maximum rate of depolarization was 1–2 v/sec and the action potential duration varied from 250 milliseconds to much longer periods. Membrane reversal of up to 10 mv sometimes occurred. Total resistance decreased during depolarization and recovered during repolarization. Typical biphasic potentials were also recorded with extracellular electrodes. Their amplitude (peak to peak) varied from 0.3 to several millivolts and their duration (peak to peak) from 10–40 milliseconds. Reduction of external sodium concentration to as little as one-ninth normal (choline chloride or sucrose replacement) did not reduce the amplitudes of the resting or action potentials measured intracellularly or extracellularly, but decreased the action potential frequency. Membrane reversal still occurred with intracellular electrodes and the maximum rate of depolarization was unchanged. The rate of repolarization was increased so that the total duration of the action potential was 150 to 200 milliseconds. With extracellular electrodes, the peak to peak amplitudes were increased and the durations were unchanged. Further reduction of external sodium concentration to less than 15–20 meq/liter caused a contraction without further change in action potential configuration. Gradual relaxation and slowing of the repetition rate of action potentials occurred and resulted eventually in complete mechanical and electrical inactivity.Rabbit taenia coli were also studied and their electrical properties contrasted to those of cat myometrium. The conclusions were reached that: (1) the available evidence opposes the hypotheses that an inward sodium current accounts for depolarization in smooth muscle and (2) smooth muscles differed in their electrical properties and mechanisms of ion distribution not only from striate muscles but also from one another.

Facilitated diffusion of monosaccharides in smooth muscle of rat vas deferens in vitro

1984 ◽  
Vol 62 (9) ◽  
pp. 1112-1115 ◽  
Author(s):  
J. Elbrink
Keyword(s):  
Smooth Muscle ◽  
Vas Deferens ◽  
Contractile Activity ◽  
Sugar Transport ◽  
Insulin Receptors ◽  
Rat Vas Deferens ◽  
Diffusion System ◽  
Facilitated Diffusion ◽  
High Concentration

The suitability of rat vas deferens for investigating sugar transport in smooth muscle was determined in vitro, with the nonmetabolized glucose analog 3-O-methyl-D-glucose as test sugar. Vas deferens smooth muscle contains a facilitated diffusion system for monosaccharides, as shown by saturation of the transport sites and by competition between 3-O-methyl-D-glucose and D-glucose. The activity of the facilitated diffusion system could be enhanced by hyperosmolarity and by contractile activity, but frequency dependency could not be established. A high concentration of insulin (100 mU/mL) was required to stimulate sugar transport. As smooth muscle is not a primary tissue for the storage of energy reserves, it does not require large numbers of insulin receptors.

Changes in resting membrane potential induced by active sensitization in the guinea-pig vas deferens

1998 ◽  
Vol 76 (7-8) ◽  
pp. 802-806 ◽  
Author(s):  
J Noireaud ◽  
O Souilem ◽  
S Baudet ◽  
J -C Bidon ◽  
M Gogny ◽  
...  
Keyword(s):  
Smooth Muscle ◽  
Membrane Potential ◽  
Guinea Pig ◽  
Smooth Muscle Cells ◽  
Vas Deferens ◽  
Smooth Muscles ◽  
Muscle Cells ◽  
Resting Membrane Potential ◽  
Ouabain Binding

Smooth muscles hyperresponsiveness is a common feature in anaphylaxis and allergic diseases. The aim of the present work was to investigate whether the enhanced reactivity of sensitized guinea-pig vas deferens was associated with changes in the resting membrane potential (Er) of the smooth muscle cells. Active sensitization was performed by subcutaneous injection of egg albumen. Er was measured in vitro in isolated vas deferens with conventional KCl-filled microelectrodes. Quantification of [3H]ouabain binding sites, measurements of 86Rb efflux, and measurements of Na and K contents were also performed. In normal physiological solution, at 35°C, Er was a mean of -54.1 ± 0.3 mV (mean ± SEM) in control vas deferens. Sensitization resulted in depolarizing Er by about 7 mV. In control and sensitized preparations, the 3H-ouabain binding site concentration, the efflux of 86Rb, and the K content were similar. In guinea-pig vas deferens, active sensitization induced a partial depolarization of the resting membrane potential of the smooth muscle cells, which did not result from a downregulation of Na+-K+ pump sites.Key words: hyperreactivity, sensitization, Na+-K+ ATPase, guinea-pig, vas deferens, smooth muscle.

Role of serine-threonine phosphoprotein phosphatases in smooth muscle contractility

2013 ◽  
Vol 304 (6) ◽  
pp. C485-C504 ◽  
Author(s):  
Trent Butler ◽  
Jonathan Paul ◽  
Nick Europe-Finner ◽  
Roger Smith ◽  
Eng-Cheng Chan
Keyword(s):  
Smooth Muscle ◽  
Smooth Muscles ◽  
Smooth Muscle Contraction ◽  
Regulatory Subunit ◽  
Muscle Contractility ◽  
Smooth Muscle Contractility ◽  
Healthy Pregnancy ◽  
Convergence Point ◽  
The Many

The degree of phosphorylation of myosin light chain 20 (MLC20) is a major determinant of force generation in smooth muscle. Myosin phosphatases (MPs) contain protein phosphatase (PP) 1 as catalytic subunits and are the major enzymes that dephosphorylate MLC20. MP regulatory targeting subunit 1 (MYPT1), the main regulatory subunit of MP in all smooth muscles, is a key convergence point of contractile and relaxatory pathways. Combinations of regulatory mechanisms, including isoform splicing, multiple phosphorylation sites, and scaffolding proteins, modulate MYPT1 activity with tissue and agonist specificities to affect contraction and relaxation. Other members of the PP1 family that do not target myosin, as well as PP2A and PP2B, dephosphorylate a range of proteins that affect smooth muscle contraction. This review discusses the role of phosphatases in smooth muscle contractility with a focus on MYPT1 in uterine smooth muscle. Myometrium shares characteristics of vascular and other visceral smooth muscles yet, during healthy pregnancy, undergoes hypertrophy, hyperplasia, quiescence, and labor as physiological processes. Myometrium presents an accessible model for the study of normal and pathological smooth muscle function, and a better understanding of myometrial physiology may allow the development of novel therapeutics for the many disorders of myometrial physiology from preterm labor to dysmenorrhea.

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