THE ELECTRICAL PROPERTIES OF THE SMOOTH MUSCLE CELL MEMBRANE

1958 ◽  
Vol 36 (1) ◽  
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.

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.

scholarly journals Maximum Rate of Depolarization of Single Muscle Fiber in Normal and Low Sodium Solutions

1965 ◽  
Vol 49 (1) ◽  
pp. 17-25 ◽  
Author(s):  
Arnaldo Ferroni ◽  
Donatella Blanchi
Keyword(s):  
Action Potentials ◽  
Maximum Rate ◽  
Sodium Current ◽  
Sodium Concentration ◽  
Single Muscle ◽  
Membrane Action ◽  
Independence Principle ◽  
Low Sodium ◽  
Intracellular Microelectrodes ◽  
Normal Tyrode Solution

The values of membrane action potentials and maximum depolarization rates of single muscle fibers in normal Tyrode solution and in low sodium solutions containing as little as 20 per cent of the sodium chloride were measured with intracellular microelectrodes. Under these conditions the membrane potential remains unchanged up to 36 per cent of [Na+]out concentration, whereas the overshoot of the action potential varies linearly with the logarithm of the external sodium concentration. The maximum depolarization rate is a linear function of the external sodium concentration. The results obtained support the ionic theory for sodium and the independence principle for sodium current related to the external sodium concentration.

Effect of sodium deficiency of the action potential of the smooth muscle of ureter

1964 ◽  
Vol 206 (1) ◽  
pp. 205-210 ◽  
Author(s):  
Makoto Kobayashi ◽  
Hiroshi Irisawa
Keyword(s):  
Smooth Muscle ◽  
Action Potential ◽  
Action Potentials ◽  
Essential Role ◽  
Choline Chloride ◽  
Resting Potential ◽  
Sodium Deficiency ◽  
Repolarization Phase ◽  
Extracellular Sodium

Action potentials of the smooth muscle of cat ureter were studied by using ultramicroelectrodes. Among 193 penetrations, the resting potential averaged 45 mv and the amplitude of action potential 32 mv. In four instances a slight overshoot was recorded. Action potential consisted of a relatively rapid rising phase followed by a slow repolarization phase, and its duration was about 0.3 sec. Effects of sodium deficiency on action potential were studied by using three different sodium substitutes. Both the height and the rising rate of action potential decreased as the concentration of extracellular sodium was reduced, indicating that the action potential of ureter muscle can be explained on the basis of sodium theory. The duration of the action potential was prolonged when sucrose or choline chloride was used as a sodium substitute; on the other hand, it shortened when tris chloride was employed. The essential role of sodium ions in the development of the action potential in ureter muscle is discussed.

Calcium action potentials in single freshly isolated smooth muscle cells

1980 ◽  
Vol 239 (5) ◽  
pp. C162-C174 ◽  
Author(s):  
J. V. Walsh ◽  
J. J. Singer
Keyword(s):  
Smooth Muscle ◽  
Action Potential ◽  
Smooth Muscle Cells ◽  
Action Potentials ◽  
Maximum Rate ◽  
Muscle Cells ◽  
Membrane Resistance ◽  
Inward Current ◽  
Visceral Smooth Muscle ◽  
Maximum Rate Of Rise

The ionic basis of the action potential was investigated using intracellular microelectrodes in single smooth muscle cells freshly isolated from the stomach of the toad Bufo marinus. When [Ca2+]0 was elevated (> 8mM), action potentials were readily elicited, which had similar characteristics to those found in many tissue preparations of visceral smooth muscle. There was a decrease in membrane resistance at the peak of the action potential and during the undershoot. The following evidence indicated that the inward current is carried by Ca2+: 1) Raising [Ca2+]0 from 15 to 49.6 mM in the presence of 18.2 mM tetraethylammonium chloride (TEA) increased the maximum rate of rise and the overshoot amplitude, the latter by 15 mV, i.e., 29.5 mV/10-fold change in [Ca2+]0. Changing [Na2+]0 from 11.8 to 81.8 mM had no significant effect on the maximum rate of rise or the overshoot. 2) The action potentials were blocked by 8 mM Mn2+ ([Ca2+]0 = 14.6 mM) but not by 14.3 microM tetrodotoxin (TTX) ([Na2+]0 = 100 mM). 3) Action potentials could be elicited when [Ba2+]0 or [Sr2+]0 were present in high concentrations ([Ca2+]0 less than or equal to 31 microM,[Na2+]0 = 11.8 mM). Both the maximum rate of rise and overshoot amplitude of the action potential increased as the membrane potential became more negative, suggesting increased activation of the inward current. Both TEA and Ba2+ prolonged the action potential, suggesting that a K+ current is responsible for repolarization. Action potentials could also be elicited on anode break at elevated [K+]0 (91 mM).

Isolated Giant Smooth Muscle Fibres in Beroe Ovata: Ionic Dependence of Action Potentials Reveals Two Distinct Types of Fibre

1988 ◽  
Vol 135 (1) ◽  
pp. 343-362 ◽  
Author(s):  
ANDRÉ BILBAUT ◽  
ROBERT W. MEECH ◽  
MARI-LUZ HERNANDEZ-NICAISE
Keyword(s):  
Smooth Muscle ◽  
Action Potential ◽  
Action Potentials ◽  
Marine Invertebrate ◽  
The Body ◽  
Fibre Types ◽  
Resting Membrane Potential ◽  
Muscle Fibres ◽  
Beroe Ovata ◽  
Radial Muscle

1. The ionic dependence of action potentials evoked in giant smooth muscle fibres isolated by enzymatic digestion from the body wall of the marine invertebrate Beroe ovata (Ctenophora) has been investigated using conventional electrophysiological techniques. 2. Differences were observed in the two fibre types studied. The resting membrane potential was −60 ± 1.35 mV (N = 25) in longitudinal muscle fibres and −66 ±1.37 mV (N=32) in radial fibres. Action potentials had a short plateau in longitudinal fibres but not in radial fibres. 3. The action potential overshoot of both fibre types was decreased in Ca2+-free artificial sea water (ASW). In Na+-deficient ASW, action potentials could not be generated in radial fibres and showed a reduced overshoot in longitudinal fibres. 4. Tetrodotoxin (10−5moll−5) added to ASW or Ca2+-free ASW did not affect the action potentials of either type of fibre. 5. Action potentials of both fibres were partially blocked by Co2+ (20–50 mmoll−1) or Cd2+ (l-2mmoll−1). Action potentials of longitudinal fibres in Na+-deficient ASW were abolished by Co2+ (20mmoll−1). In Ca2+-free ASW, the ction potential overshoots of both sets of fibres were restored following the addition of Sr2+ or Ba2+. In longitudinal fibres, Sr2+ increased the duration of the action potential plateau. In both longitudinal and radial muscle fibres, Ba2+ prolonged the action potential. 6. In longitudinal fibres exposed to tetraethylammonium chloride (TEAC1) or 4-aminopyridine (4AP), the action potential was slightly prolonged. In these fibres, TEA+ or 4AP added to Ca2+-free ASW induced only a long-lasting depolarizing plateau. In radial fibres, the action potential duration was slightly increased in the presence of TEA+; it was unaffected by 4AP. In Ca2+-free ASW, TEA+ and 4AP induced an oscillating membrane response which appeared to be dependent on the intensity of the injected current pulse. 7. It is concluded that (a) there are significant differences between the action potentials of longitudinal and radial muscle fibres but that both are dependent on Na+ and Ca2+, (b) in longitudinal fibres, a Ca2+-activated K+ conductance and a TEA+-sensitive voltage-activated K+ conductance contribute to the repolarizing phase of the action potential, the former being predominant, (c) in radial fibres, the repolarizing phase of action potentials probably involves different membrane K+ conductances among which is a TEA+-sensitive K+ conductance.

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.

Cholinergic nerve-mediated excitation in the guinea pig choledochoduodenal junction activated by distension

1994 ◽  
Vol 267 (5) ◽  
pp. G938-G946 ◽  
Author(s):  
F. Vogalis ◽  
R. R. Bywater ◽  
G. S. Taylor
Keyword(s):  
Smooth Muscle ◽  
Guinea Pig ◽  
Action Potential ◽  
Action Potentials ◽  
Discharge Rate ◽  
Circular Muscle ◽  
Muscle Layer ◽  
Circular Muscle Layer ◽  
Circular Layer ◽  
Longitudinal Layer

The electrical basis of propulsive contractions in the guinea pig choledochoduodenal junction (CDJ), which are triggered by distension, was investigated using intracellular microelectrode recording techniques. The isolated CDJ was placed in a continuously perfused tissue chamber at 37 degrees C. Membrane potential was recorded from smooth muscle cells in either the ampulla or in the upper CDJ (upper junction) regions, which were immobilized by pinning. Distension of the upper junction (20-30 s) by increasing intraductal hydrostatic pressure (mean elevation: 2.0 +/- 0.3 kPa, n = 13) triggered "transient depolarizations" (TDs: < 5 mV in amplitude and 2-5 s in duration) and action potentials in the circular muscle layer of the ampulla. The frequency of TDs in the ampulla was increased from 2.2 +/- 0.2 to 15.9 +/- 2.2 min-1 (n = 13) during distension. Simultaneous impalements of cells in the longitudinal and circular muscle layers in the ampulla revealed that subthreshold TDs in the circular layer were associated with an increased rate of action potential discharge in the longitudinal layer. Atropine (Atr; 1.4 x 10(-6) M) and tetrodotoxin (TTX; 3.1 x 10(-6) M blocked the distension-evoked increase in TD frequency, without affecting the frequency of ongoing TDs. The sulfated octapeptide of cholecystokinin (1-5 x 10(-8) M) increased the amplitude of TDs recorded in the circular muscle layer of the ampulla and increased action potential discharge rate. In separate recordings, radial stretch of the ampulla region increased the rate of discharge of action potentials in the smooth muscle of the upper junction.(ABSTRACT TRUNCATED AT 250 WORDS)

Effects of moderate hypoxia on premature action potentials of rabbit papillary muscle

1984 ◽  
Vol 62 (5) ◽  
pp. 596-599
Author(s):  
Julio Alvarez ◽  
Francisco Dorticós ◽  
Jesús Morlans
Keyword(s):  
Action Potential ◽  
Action Potential Duration ◽  
Action Potentials ◽  
Potassium Current ◽  
Maximum Rate ◽  
Resting Potential ◽  
Papillary Muscles ◽  
Premature Response ◽  
Coupling Interval ◽  
Control Response

Experiments were performed to study the effects of hypoxia on the characteristics of premature action potentials of rabbit papillary muscles. At normal resting potential, the duration of the premature action potential at the shortest coupling intervals was always greater than that of the control response. As the coupling interval was increased beyond 150 ms, the duration of the premature action potential regained control values. In cells depolarized to −70 mV by KCl, early lengthening of the premature response was attenuated. After 60 min of hypoxia, recovery of action potential duration at normal and reduced resting potentials was accelerated. The maximum rate of depolarization and its reactivation time constant were not affected by 60 min of hypoxia. It is suggested that intracellular free Ca is important in the control of action potential duration via the outward background potassium current.

scholarly journals Mathematical Distinction in Action Potential between Primo-Vessels and Smooth Muscle

2012 ◽  
Vol 2012 ◽  
pp. 1-6 ◽  
Author(s):  
Seong-Jin Cho ◽  
Sang-Hun Lee ◽  
Wenji Zhang ◽  
Sae-Bhom Lee ◽  
Kwang-Ho Choi ◽  
...  
Keyword(s):  
Fourier Transform ◽  
Smooth Muscle ◽  
Action Potential ◽  
Mathematical Analysis ◽  
Action Potentials ◽  
Type I ◽  
Type Ii ◽  
Analysis Method

We studied the action potential of Primo-vessels in rats to determine the electrophysiological characteristics of these structures. We introduced a mathematical analysis method, a normalized Fourier transform that displays the sine and cosine components separately, to compare the action potentials of Primo-vessels with those for the smooth muscle. We found that Primo-vessels generated two types of action potential pulses that differed from those of smooth muscle: (1) Type I pulse had rapid depolarizing and repolarizing phases, and (2) Type II pulse had a rapid depolarizing phase and a gradually slowing repolarizing phase.

The dependence of the maximum rate of rise of the action potential upstroke on membrane properties

1981 ◽  
Vol 214 (1194) ◽  
pp. 85-98 ◽  
Keyword(s):  
Action Potential ◽  
Maximum Rate ◽  
Sodium Current ◽  
Membrane Properties ◽  
Fractional Change ◽  
Sodium Conductance ◽  
Excitable Membranes ◽  
Real Relation ◽  
Voltage Clamping ◽  
Maximum Rate Of Rise

The maximum rate of rise of the action potential ( V̇ max ) is often used to study the maximum sodium conductance ( Ḡ Na ) of excitable membranes, by assuming that V̇ max is proportional to Ḡ Na . However, the real relation between V̇ max and Ḡ Na is uncertain. We use simple analytical descriptions of the membrane currents to investigate this relation. If (1) the sodium conductance is much greater than the non-sodium conductance of the membrane, (2) the sodium current is activated extremely quickly, and (3) the sodium current is inactivated extremely slowly, then V̇ max will indeed be proportional to Ḡ Na . However, if conditions (1) or (3) are not satisfied, the V̇ max – Ḡ Na relation will be non-proportional, such that a certain fractional change of Ḡ Na produces a larger fractional change of V̇ max . If condition (2) is not satisfied the V̇ max – Ḡ Na relation is distorted in the opposite direction, such that a certain fractional change of Ḡ Na produces a smaller fractional change of V̇ max . Measurements of V̇ max are usually performed in preparations where voltage clamping cannot be used to study Ḡ Na directly. However, voltage clamping is necessary to verify that conditions (1)–(3) are satisfied. The results of studies using V̇ max alone as a measure of Ḡ Na should be assessed with caution.

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