Cardiac Ganglion of Limulus: Intracellular Activity in the Unipolar Cells

1970 ◽  
Vol 53 (2) ◽  
pp. 411-423
Author(s):  
VINCENT J. PALESE ◽  
JANE L. BECKER ◽  
RALPH A. PAX
Keyword(s):  
Functional Relationship ◽  
Membrane Resistance ◽  
Recovery Phase ◽  
Resting Membrane Potential ◽  
Cardiac Ganglion ◽  
External Stimulation ◽  
A Value ◽  
Number Of Factors ◽  
Soma Membrane ◽  
Specific Membrane

1. The electrical activity of unipolar cells of the cardiac ganglion of Limulus has been examined with microelectrodes to determine the electrical properties and the functional relationship between unipolar cells. 2. Resting membrane potential in these cell averages -43 mV. 3. Correlated with each contraction of the heart there occurs a burst of activity which consists of a sustained depolarization of several seconds on which is superimposed a series of small 2-5 mV spikes. 4. Activity which occurs during the initial phase appears to be the result of pre-synaptic inputs to these cells. Spike activity during the recovery phase is probably endogenous to the cell from which we are recording. 5. The specific membrane resistance for the soma membrane averages 12700Ω.cm2. The time constant has a value of 19.6ms. The specific membrane capacitance measures endogenous to the cell from which we are recording. 6. External stimulation produces a number of different responses in the unipolar cells which are dependent upon a number of factors. These responses can be classified into at least three types: (a) a driven response similar to a spontaneous burst; (b) slowly rising potentials which may be antidromic spikes.

Electrical and Mechanical Properties of the Red and White Muscles in the Silver Carp

1972 ◽  
Vol 57 (2) ◽  
pp. 551-567
Author(s):  
T. YAMAMOTO
Keyword(s):  
Mechanical Properties ◽  
White Muscle ◽  
Silver Carp ◽  
Membrane Resistance ◽  
Resting Potential ◽  
Resting Membrane Potential ◽  
Mechanical Responses ◽  
Red Muscle ◽  
Red And White Muscles ◽  
Specific Membrane

1. Electrical and mechanical properties of the red muscle (M. levator pinnae pectoralis) and white muscle (M. levator pinnae lateralis abdominis) in the silver carp (Carassius auratus Linné) were investigated by using caffeine and thymol. 2. A complete tetanus could be produced in the red muscle. But in the white muscle no tetanus was produced and there was a gradual decrease in tension during continuous stimulation, even at a frequency of 1 c/s or less. 3. Caffeine (0.5-1 mM) and thymol (0.25-0.5 mM) potentiated the twitch tension in both muscles without an increase in the resting tension; they produced a contracture in both muscles when the concentration was increased further. 4. The falling phase of the active state of contraction was nearly the same in both muscles and was prolonged by caffeine (0.5 mmM) and by thymol (0.25 mM). 5. The resting membrane potential of the red muscle was scarcely affected by caffeine (0.5-5 mM), whereas in the white muscles a depolarization of 10 mV was observed with caffeine of more than 2 mM. The resting potential of both muscles was little changed by o.25 mm thymol. However, at a concentration of more than 0.5mM thymol depolarized the membrane in both muscles to the same extent. 6. In caffeine (2-3 mM) solution the mean specific membrane resistance was reduced from 8.8 kΩ cm2 to 6.0 kΩ cm2 in the red muscle, and from 5.0 kΩ cm2 to 2.7 kΩ cm2 in the white muscle. In thymol (0.5-1 mM) solution it was reduced from 11.2 kΩcm2 to 6.5 kΩ cm2 in the red muscle, and from 5.4kΩ cm2 to 3.1 kΩ) cm2 in the white muscle. The specific membrane capacitance, calculated from the time constant and the membrane resistance, remained more or less the same in both muscles after a treatment with these agents. 7. Electrical properties of the muscles and the effects of caffeine and thymol on mechanical responses suggest that there are no fundamental differences between red and white muscles except for the excitation-contraction coupling. A lack of summation of twitch, a successive decline of twitch, and inability to produce potassium contracture in the white muscle may be due to the fact that the Ca-releasing mechanism is easily inactivated by depolarization of the membrane.

scholarly journals Electrical Properties and Excitation-Contraction Coupling in Skeletal Muscle Treated with Ethylene Glycol

1972 ◽  
Vol 60 (2) ◽  
pp. 221-236 ◽  
Author(s):  
Carlos Sevcik ◽  
Toshio Narahashi
Keyword(s):  
Membrane Potential ◽  
Ethylene Glycol ◽  
Control Level ◽  
Membrane Resistance ◽  
Ringer Solution ◽  
Resting Membrane Potential ◽  
Sartorius Muscle ◽  
Frog Sartorius ◽  
Specific Membrane ◽  
Normal Ringer

The contractility of the frog sartorius muscle was suppressed after treatment with a Ringer solution added with ethylene glycol (EGR). No contraction was elicited by nerve stimulation when the muscle was brought back to normal Ringer solution after having been soaked in 876 mM EGR for 4 hr or in 1095 mM EGR for 2 hr. However, the action potential of normal amplitude was generated and followed by a depolarizing afterpotential. The resting membrane potential was slightly decreased from the mean normal value of –91.1 mv to –78.8 mv when 1095 mM EGR was used, and to –82.3 mv when 876 mM EGR was used, but remained almost constant for as long as 2 hr. The afterpotential that follows a train of impulses and a slow change in membrane potential produced by a step hyperpolarizing current (so-called "creep") were suppressed after treatment with ethylene glycol. The specific membrane capacity decreased to about 50% of the control values while the specific membrane resistance increased to about twice the control values Therefore, the membrane time constant remained essentially unchanged. The water content of the muscle decreased by about 30% during a 2 hr immersion in 1095 mM EGR, and increased by about 30% beyond the original control level after bringing the muscle back to normal Ringer. The intracellular potassium content did not change significantly during these procedures. Some differences between the present results and those obtained with glycerol are discussed.

Magnesium affects excitation, conduction, and contraction of isolated mammalian cardiac muscle

1992 ◽  
Vol 263 (2) ◽  
pp. H622-H633 ◽  
Author(s):  
S. K. Hall ◽  
C. H. Fry
Keyword(s):  
Ventricular Myocytes ◽  
Mammalian Species ◽  
Negative Inotropic Effect ◽  
Membrane Resistance ◽  
Resting Membrane Potential ◽  
Activation Curve ◽  
Voltage Dependent ◽  
Inward Currents ◽  
Specific Membrane ◽  
Action Potential Configuration

An increase of extracellular Mg concentration, [Mg]o, reduced myocardial excitability and conduction without affecting the resting membrane potential or action potential configuration in ventricular myocytes and papillary muscles from a number of mammalian species. Although there was a small increase of specific membrane resistance and no change to intracellular resistivity, the threshold voltage was shifted to depolarized potentials. Thus loss of excitability can be explained by a shift of the activation of inward currents to depolarized potentials, and reduced conduction velocity is due solely to a diminution of local circuit currents. Mgo also was negatively inotropic, the magnitude of this effect being species dependent. Raised [Mg]o caused a small increase of intracellular [Mg] with a small decrease of intracellular [Na+], did not affect intracellular pH, and attenuated the intracellular Ca2+ transient associated with cell shortening in rat (but not rabbit) myocytes. An increase of [Mg]o reduced the magnitude of the voltage-dependent inward Ca2+ current, ICa, in rat and rabbit myocytes, and the activation curve of ICa was shifted to more depolarized potentials. A scheme to account for the negative inotropic effect of Mg is presented.

scholarly journals The Electrical Constants of the Fibres from Two Leg Muscles of the Locust Schistocerca Gregaria

1987 ◽  
Vol 127 (1) ◽  
pp. 173-189 ◽  
Author(s):  
M. E. KORNHUBER ◽  
C. WALTHER
Keyword(s):  
Schistocerca Gregaria ◽  
Potential Temperature ◽  
Fibre Diameter ◽  
Membrane Resistance ◽  
Retractor Muscle ◽  
Resting Membrane Potential ◽  
Mean Values ◽  
Membrane Capacity ◽  
Length Constant ◽  
Specific Membrane

1. The passive electrical properties of the fibres from the M. extensor tibiae and the M. retractor unguis in the hindleg of the locust Schistocerca gregaria were investigated using short cable theory. The dependence on various physicochemical parameters was determined. 2. The sarcoplasmic resistivity (R1) was the same in the extensor and in the retractor muscle. R1 was ≊ 175 Ωcm at 20°C. 3. The specific membrane resistance (Rm) was considerably lower in the retractor muscle (≊5100 Ωcm2) than in the extensor muscle (≊13 000 Ωcm2; [K+]o =; 10 mmoll−1; temperature = 20°C). Rm increased by more than 100 % if the external potassium concentration was lowered from 10 to 5 mmoll−1 and it decreased by approximately 75 % if the calcium concentration was lowered from 2 to 0.2 mmoll−1. 4. The specific membrane capacity (Cm) increased with fibre diameter. The different mean values for Cm in the extensor (8.5 μF cm−2) and retractor muscle (6.3 μF cm−2) can be accounted for by the different mean fibre diameters. 5. The temperature coefficients (Q10) of the electrical constants were 0.74 for Ri, 0.48 for Rm, 1.01 for Cm and 1.21 for the resting membrane potential (temperature, 16–27°C). 6. There was close agreement between the membrane time constant (τm) derived from the decay of the excitatory junction potential (EJP) and that derived from injection of current pulses. Thus Rm and the length constant (λ) can be derived from the EJP and the fibre diameter if the sarcoplasmic resistivity and the specific membrane capacity are known. 7. The temporospatial dependence of miniature EJPs in a fibre can be predicted satisfactorily from the electrical constants as is demonstrated by an example given in the Appendix. Note: Dedicated to the late Graham Hoyle

Membrane resistance increases when automaticity develops in explanted rat heart cells

1990 ◽  
Vol 258 (1) ◽  
pp. H145-H152 ◽  
Author(s):  
O. F. Schanne ◽  
M. Lefloch ◽  
B. Fermini ◽  
E. Ruiz-Petrich
Keyword(s):  
Spontaneous Activity ◽  
Action Potentials ◽  
Ventricular Myocytes ◽  
Input Resistance ◽  
Membrane Resistance ◽  
Resting Potential ◽  
Heart Cells ◽  
Membrane Capacity ◽  
Rat Heart Cells ◽  
Specific Membrane

We compared the passive electrical properties of isolated ventricular myocytes (resting potential -65 mV, fast action potentials, and no spontaneous activity) with those of 2- to 7-day-old cultured ventricle cells from neonatal rats (resting potential -50 mV, slow action potentials, and presence of spontaneous activity). In myocytes the specific membrane capacity was 0.99 microF/cm2, and the specific membrane resistance increased from 2.46 k omega.cm2 at -65 mV to 7.30 k omega.cm2 at -30 mV. In clusters, the current-voltage relationships measured under current-clamp conditions showed anomalous rectification and the input resistance decreased from 1.05 to 0.48 M omega when external K+ concentration was increased from 6 to 100 mM. Using the model of a finite disk we determined the specific membrane resistance (12.9 k omega.cm2), the effective membrane capacity (17.8 microF/cm2), and the lumped resistivity of the disk interior (1,964 omega.cm). We conclude that 1) the voltage dependence of the specific membrane resistance cannot completely explain the membrane resistance increase that accompanies the appearance of spontaneous activity; 2) a decrease of the inwardly rectifying conductance (gk1) is mainly responsible for the increase in the specific membrane resistance and depolarization; and 3) approximately 41% of the inward-rectifying channels are electrically silent when spontaneous activity develops in explanted ventricle cells.

Postnatal Development of Electrophysiological Properties of Nucleus Accumbens Neurons

2000 ◽  
Vol 84 (5) ◽  
pp. 2204-2216 ◽  
Author(s):  
Marc L. Belleau ◽  
Richard A. Warren
Keyword(s):  
Nucleus Accumbens ◽  
Postnatal Development ◽  
Action Potentials ◽  
Membrane Resistance ◽  
Inward Rectification ◽  
Resting Membrane Potential ◽  
Projection Neurons ◽  
Patch Clamp Technique ◽  
Whole Cell ◽  
Wide Range

We have studied the postnatal development of the physiological characteristics of nucleus accumbens (nAcb) neurons in slices from postnatal day 1 ( P1) to P49 rats using the whole cell patch-clamp technique. The majority of neurons (102/108) were physiologically identified as medium spiny (MS) projection neurons, and only these were subjected to detailed analysis. The remaining neurons displayed characteristics suggesting that they were not MS neurons. Around the time of birth and during the first postnatal weeks, the membrane and firing characteristics of MS neurons were quite different from those observed later. These characteristics changed rapidly during the first 3 postnatal weeks, at which point they began to resemble those found in adults. Both whole cell membrane resistance and membrane time constant decreased more than fourfold during the period studied. The resting membrane potential (RMP) also changed significantly from an average of −50 mV around birth to less than −80 mV by the end of the third postnatal week. During the first postnatal week, the current-voltage relationship of all encountered MS neurons was linear over a wide range of membrane potentials above and below RMP. Through the second postnatal week, the proportion of neurons displaying inward rectification in the hyperpolarized range increased steadily and after P15, all recorded MS neurons displayed significant inward rectification. At all ages, inward rectification was blocked by extracellular cesium and tetra-ethyl ammonium and was not changed by 4-aminopyridine; this shows that inward rectification was mediated by the same currents in young and mature MS neurons. MS neurons fired single and repetitive Na+/K+ action potentials as early as P1. Spike threshold and amplitude remained constant throughout development in contrast to spike duration, which decreased significantly over the same period. Depolarizing current pulses from rest showed that immature MS neurons fired action potentials more easily than their older counterparts. Taken together, the results from the present study suggest that young and adult nAcb MS neurons integrate excitatory synaptic inputs differently because of differences in their membrane and firing properties. These findings provide important insights into signal processing within nAcb during this critical period of development.

To the question of the therapeutic value of overfeeding nephrotic proteins

1937 ◽  
Vol 33 (2) ◽  
pp. 132-142
Author(s):  
A. I. Golikov ◽  
M. M. Grigorieva
Keyword(s):  
Plasma Proteins ◽  
Water Exchange ◽  
Cholesterol Metabolism ◽  
The State ◽  
The Body ◽  
Factors Associated ◽  
A Value ◽  
Number Of Factors ◽  
Therapeutic Value ◽  
Blood Plasma Proteins

The study of the problem of water exchange and issues of the pathogenesis of edema (Starling, Krog, Beilis, Schade, Gover, Shabanier, Kilin, etc.) made it possible to establish the colossal significance in the pathogenesis of nephrosis of a number of factors associated with the state of the body's proteins. To one degree or another, depletion of blood plasma proteins, sharp changes in the ratio of protein fractions with a shift towards the coarse-dispersed phase (globulins), an increase in the hydrophilicity of tissue colloids (McClure and Aldrich test) characterize pathological shifts in the protein economy of the body. The osmotic pressure of nephrotic plasma proteins drops sharply due to an increase in osmotically much less active globulins and fibrinogen (Schade, Shabanier, Gover, Kilin, Malkin, etc.). This decrease can in some cases reach a value of 10-14 cm of water column in comparison with the normal value of 30-40 cm (Gover, Golikov). According to modern views, these violations of the protein constant due to changes in the salt balance, in the state of permeability of the capillary wall and the state of tissue colloids are a common cause of the hydropic state of the body. Along with the violation of protein metabolism, changes in the state of lipoid-cholesterol metabolism occur in the body with nephrosis. The absence of contraindications for giving nephrotic protein is well known.

Oxygen pulse

2021 ◽  
pp. 51-55
Author(s):  
William J.M. Kinnear ◽  
James H. Hull
Keyword(s):  
Cardiac Output ◽  
Oxygen Uptake ◽  
Arterial Oxygen Saturation ◽  
Recovery Phase ◽  
Arterial Oxygen ◽  
Low Cardiac Output ◽  
Oxygen Pulse ◽  
A Value ◽  
Peripheral Arterial ◽  
Mixed Venous

This chapter outlines how dividing the volume of oxygen uptake (VO2) by the pulse rate gives an estimate of the stroke volume of the heart. The amount of oxygen taken up with each heartbeat is called the oxygen pulse (O2 pulse). It should increase steadily on exercise to a value above 10 ml/beat and may continue to rise during the recovery phase. A low O2 pulse can be an indicator of low cardiac output. If the maximum VO2 (VO2max) is normal, caution should be used in the interpretation of a low O2 pulse. Sometimes the O2 pulse is abnormal because of a fall in peripheral arterial oxygen saturation (SpO2) or mixed venous oxygen levels.

Properties of thyroidectomized rat extensor muscle

1978 ◽  
Vol 234 (3) ◽  
pp. C90-C95 ◽  
Author(s):  
J. Grossie
Keyword(s):  
Electrical Properties ◽  
Relaxation Times ◽  
Input Resistance ◽  
Membrane Resistance ◽  
Extensor Muscle ◽  
Resting Membrane Potential ◽  
Rat Muscle ◽  
Mechanical And Electrical Properties ◽  
Isometric Twitch ◽  
Indirect Action

Basic mechanical and electrical properties of rat extensor muscle were analyzed 4--6 wk after thyroid removal. Isometric twitch tensions in thyroidectomized (Tx) rat muscle varied considerably, with over 60% of the muscles showing abnormally low values and the remainder showing a high twitch force. The duration of the twitch was significantly increased from 137 to 245 ms but contraction and half-relaxation times were not significantly changed. Tetanic force was not effected by thyroidectomy. Electrical properties of the muscle fiber membranes were made exclusively via intracellular techniques. The resting membrane potential was slightly higher in thyroidectomized rats (-79 mV) as compared to sham controls (-78 mV). Both direct and indirect action potentials showed higher overshoots, amplitudes, and rates of depolarization in thyroidectomized rats. The threshold of the indirect action potential appeared at a higher transmembrane potential as compared to sham-operated controls. The input resistance, space constant, time constant, and specific membrane resistance were all significantly increased in thyroidectomized rat extensor muscle, whereas fiber diameter and capacitance were significantly decreased. Estimates of specific ionic conductance show that both potassium and chloride conductance are decreased in thyroidectomized rat muscle.

Electrophysiological characterization of single pregnant rat myometrial cells in short-term primary culture

1986 ◽  
Vol 250 (1) ◽  
pp. C47-C54 ◽  
Author(s):  
P. Mollard ◽  
J. Mironneau ◽  
T. Amedee ◽  
C. Mironneau
Keyword(s):  
Action Potential ◽  
Primary Culture ◽  
Membrane Resistance ◽  
Resting Potential ◽  
Short Term ◽  
Pregnant Rat ◽  
Myometrial Cells ◽  
The Mean ◽  
Electrophysiological Characterization ◽  
Specific Membrane

Smooth muscle cells were isolated from the longitudinal layer of pregnant rat myometrium (18-19 days) and studied either freshly dissociated or during short-term primary culture (until 30 h) using intracellular microelectrode techniques and direct microscopic observation. The isolated myometrial cells excluded trypan blue vital stain and could repetitively contract in response to various stimuli. Electrophysiological studies at 37 degrees C showed normal resting potential (-54.5 +/- 7.5 mV, n = 71). Action potentials with overshoot (+7.8 +/- 4.6 mV, n = 71) could be elicited by intracellular stimulation. Moreover, the membrane potential was largely dependent on the external K+ concentration. The action potential was suppressed in a Ca2+-free solution [with 0.1 mM ethyleneglycol-bis(beta-aminoethylether)-N,N'-tetraacetic acid], and the overshoot amplitude was clearly Ca2+ dependent. The action potential was inhibited by Mn2+ ions (1 mM), Co2+ ions (1 mM), and D 600 (1 microM) but was unaffected by tetrodotoxin (2 microM) and external Na+ removal. Tetraethylammonium chloride (TEA, 10 mM) and 4-aminopyridine (4-AP, 10 mM) increased both overshoot amplitude and duration of the electrical responses. When the cell surface area was measured with light microscopy, the mean specific membrane resistance was 14.8 +/- 4.6 k omega . cm2 (n = 14), and the mean specific membrane capacitance was 2.3 +/- 0.7 microF/cm2 (n = 14). Outward-going rectification was consistently observed in all cells examined. This was either inhibited by TEA and 4-AP (10 mM each) or reduced in the presence of 1 mM Mn2+.(ABSTRACT TRUNCATED AT 250 WORDS)

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