Thermal dependence of passive electrical properties of lizard muscle fibres

1987 ◽  
Vol 133 (1) ◽  
pp. 169-182 ◽  
Author(s):  
B. A. Adams
Keyword(s):  
Electrical Properties ◽  
Input Resistance ◽  
Membrane Resistance ◽  
Effect Of Temperature ◽  
Muscle Fibres ◽  
Thermal Dependence ◽  
Thermophilic Species ◽  
Length Constant ◽  
Increasing Temperature ◽  
Passive Electrical Properties

1. The thermal dependence of passive electrical properties was determined for twitch fibres from the white region of the iliofibularis (IF) muscle of Anolis cristatellus (15–35 degrees C) and Sceloporus occidentalis (15–40 degrees C), and for twitch fibres from the white (15–45 degrees C) and red (15–40 degrees C) regions of the IF of Dipsosaurus dorsalis. These species differ in thermal ecology, with Anolis being the least thermophilic and Dipsosaurus the most thermophilic. 2. Iliofibularis fibres from the three species reacted similarly to changing temperature. As temperature was increased, input resistance (Rin) decreased (average R10 = 0.7), length constant (L) decreased (average R10 = 0.9), time constant (tau) decreased (average R10 = 0.8), sarcoplasmic resistivity (Rs) decreased (average R10 = 0.8) and apparent membrane resistance (Rm) decreased (average R10 = 0.7). In contrast, apparent membrane capacitance (Cm) increased with increasing temperature (average R10 = 1.3). 3. Rin, L, tau and apparent Rm were lowest in fibres from Anolis (the least thermophilic species) and highest in fibres from Dipsosaurus (the most thermophilic species). Anolis had the largest and Dipsosaurus the smallest diameter fibres (126 and 57 micron, respectively). Apparent Cm was highest in fibres from Sceloporus, which had fibres of intermediate diameter (101 micron). Rs did not differ significantly among species. 4. The effect of temperature on the passive electrical properties of these lizard fibres was similar to that reported for muscle fibres from other ectothermic animals (crustaceans, insects, fish and amphibians) but qualitatively different from that reported for some mammalian (cat tenuissimus, goat intercostal) fibres. The changes that occur in the passive electrical properties render the fibres less excitable as temperature increases.

White noise approach for estimating the passive electrical properties of neurons

1996 ◽  
Vol 76 (5) ◽  
pp. 3442-3450 ◽  
Author(s):  
W. N. Wright ◽  
B. L. Bardakjian ◽  
T. A. Valiante ◽  
J. L. Perez-Velazquez ◽  
P. L. Carlen
Keyword(s):  
Electrical Properties ◽  
White Noise ◽  
Input Impedance ◽  
Granule Cells ◽  
Short Pulse ◽  
Input Resistance ◽  
Membrane Resistance ◽  
Somatic Membrane ◽  
Dendritic Membrane ◽  
Passive Electrical Properties

1. The passive electrical properties of whole cell patched dentate granule cells were studied with the use of zero-mean Gaussian white noise current stimuli. Transmembrane voltage responses were used to compute the first-order Wiener kernels describing the current-voltage relationship at the soma for six cells. Frequency domain optimization techniques using a gradient method for function minimization were then employed to identify the optimal electrical parameter values. Low-power white noise stimuli are presented as a favorable alternative to the use of short-pulse current inputs for investigating neuronal passive electrical properties. 2. The optimization results demonstrated that the lumped resistive and capacitive properties of the recording electrode must be included in the analytic input impedance expression to optimally fit the measured cellular responses. The addition of the electrode resistance (Re) and capacitance (Ce) to the original parameters (somatic conductance, somatic capacitance, axial resistance, dendritic conductance, and dendritic capacitance) results in a seven-parameter model. The mean Ce value from the six cells was 5.4 +/- 0.3 (SE) pF, whereas Re following formation of the patch was found to be 20 +/- 2 M omega. 3. The six dentate granule cells were found to have an input resistance of 600 +/- 20 M omega and a dendritic to somatic conductance ratio of 6.3 +/- 1.1. The electronic length of the equivalent dendritic cylinder was found to be 0.42 +/- 0.03. The membrane time constant in the soma was found to be 13 +/- 3 ms, whereas the membrane time constant of the dendrites was 58 +/- 5 ms. Incorporation of morphological estimations led to the following distributed electrical parameters: somatic membrane resistance = 25 +/- 4 k omega cm2, somatic membrane capacitance = 0.48 +/- 0.05 microF/cm2, Ri (input resistance) = 72 +/- 5 omega cm, dendritic membrane resistance = 59 +/- 4 k omega cm2, and dendritic membrane capacitance = 0.97 +/- 0.06 microF/cm2. On the basis of capacitive measurements, the ratio of dendritic surface area to somatic surface area was found to be 34 +/- 2. 4. For comparative purposes, hyperpolarizing short pulses were also injected into each cell. The short-pulse input impedance measurements were found to underestimate the input resistance of the cell and to overestimate both the somatic conductance and the membrane time constants relative to the white noise input impedance measurements.

scholarly journals The Morphology and Passive Electrical Properties of Claw Closer Neurones in Snapping Shrimp

1982 ◽  
Vol 101 (1) ◽  
pp. 307-319
Author(s):  
JOHN A. WILSON ◽  
DEFOREST MELLON
Keyword(s):  
Body Size ◽  
Electrical Properties ◽  
Cell Body ◽  
Input Resistance ◽  
Proximal Portion ◽  
Snapping Shrimp ◽  
Length Constant ◽  
The Difference ◽  
Passive Electrical Properties ◽  
Cell Body Size

The morphology and passive electrical properties of the dimorphic pincer and snapper claw closer neurones were examined in the snapping shrimp, Alpheus heterochelis. No differences were found between homologous pincer and snapper neurones for input resistance and length constant in the proximal portion of the axons, or for the proximal axonal and dendritic anatomies using intracellular cobalt staining. To determine the effect of cell body size upon the passive electrical properties of the neurones, we modelled the neurones by computer. The difference in cell body size causes less than a 3% change in the electrical properties of the neurone at the axon root. Thus, despite the striking behavioural dissimilarities between the pincer and snapper claws, there is no electrical or morphological basis in the claw closer neurones for this difference.

Structure and electrical properties of eye muscles in cave- and surface-dwelling crayfishes

1980 ◽  
Vol 84 (1) ◽  
pp. 187-199
Author(s):  
D. Mellon ◽  
G. Lnenicka
Keyword(s):  
Input Resistance ◽  
Selective Advantage ◽  
Oculomotor System ◽  
Membrane Resistance ◽  
Muscle Fibres ◽  
Cross Sectional ◽  
Eye Muscles ◽  
Current Voltage ◽  
The Difference ◽  
Cave Dweller

The morphologies and passive electrical parameters of fibres in two eye muscles of a surface- and a cave-dwelling crayfish were compared. In the cave-dwelling form the muscles contained fewer fibres, of less diameter, and hence had a smaller cross-sectional area. Current-voltage relationships were similar in both species. Input resistance was higher in the cave-dweller, but the difference was not as great as would be expected on the basis of geometry alone. Accordingly, the specific membrane resistance of muscle fibres in the cave-dweller is 50–60% smaller than that in the surface-dweller. This may account partially for the observation that identified excitatory junctional potentials in muscles of cave- and surface dwellers have similar amplitudes. We conclude that a functional oculomotor system is maintained in cave-dwelling crayfish, and that this system confers some positive selective advantage.

scholarly journals Electrical Properties and Acetylcholine Sensitivity of Singly and Multiply Innervated Avian Muscle Fibers

1969 ◽  
Vol 53 (5) ◽  
pp. 624-637 ◽  
Author(s):  
M. R. Fedde
Keyword(s):  
Electrical Properties ◽  
Latissimus Dorsi ◽  
Membrane Resistance ◽  
Muscle Fiber Types ◽  
Fiber Types ◽  
Receptor Sites ◽  
Avian Muscle ◽  
Anterior Latissimus Dorsi ◽  
Length Constant ◽  
Low Sensitivity

Membrane constants and distribution of acetylcholine (ACh) receptors were determined for multiply innervated fibers of the anterior latissimus dorsi (ALD) and singly innervated fibers of the posterior latissimus dorsi (PLD) muscles of 3–6 month old chickens. The values of the various membrane constants were: length constant, 1.78 mm (mean) in ALD, 0.68 mm in PLD; time constant, 35 msec in ALD, 3.7 msec in PLD; transverse membrane resistance, 4388 Ω cm2 in ALD, 561 Ω cm2 in PLD; and membrane capacitance, 8.2 µF/cm2 in ALD, 7.0 µF/cm2 in PLD. Peaks of ACh sensitivity occurred at intervals of ca. 740 µ on ALD fibers with a low sensitivity remaining between peaks. Only one peak of ACh sensitivity was detected on PLD fibers. The maximum ACh sensitivity found was 5 ± 4 mv/ncoul for fibers of the ALD and 77 ± 60 mv/ncoul for fibers of the PLD. The distance over which this sensitivity fell to 0.1 was ca. 225 µ in the ALD and 140 µ in the PLD. The membranes of these two muscle fiber types differ widely regarding some electrical properties and the disposition of ACh-sensitive receptor sites.

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.

scholarly journals Capacitance of the Surface and Transverse Tubular Membrane of Frog Sartorius Muscle Fibers

1969 ◽  
Vol 53 (3) ◽  
pp. 265-278 ◽  
Author(s):  
Peter W. Gage ◽  
Robert S. Eisenberg
Keyword(s):  
Electrical Properties ◽  
Time Course ◽  
Muscle Fibers ◽  
Membrane Resistance ◽  
Ringer Solution ◽  
Sartorius Muscle ◽  
Tubular Membrane ◽  
Essentially Normal ◽  
The Difference ◽  
Passive Electrical Properties

The passive electrical properties of glycerol-treated muscle fibers, which have virtually no transverse tubules, were determined. Current was passed through one intracellular microelectrode and the time course and spatial distribution of the resulting potential displacement measured with another. The results were analyzed by using conventional cable equations. The membrane resistance of fibers without tubules was 3759 ± 331 ohm-cm2 and the internal resistivity 192 ohm-cm. Both these figures are essentially the same as those found in normal muscle fibers. The capacitance of the fibers without tubules is strikingly smaller than normal, being 2.24 ± 0.14 µF/cm2. Measurements were also made of the passive electrical properties of fibers in a Ringer solution containing 400 mM glycerol (which is used in the preparation of glycerol-treated fibers). The membrane resistance and capacitance are essentially normal, but the internal resistivity is somewhat reduced. These results show that glycerol in this concentration does not directly affect the membrane capacitance. Thus, the figure for the capacitance of glycerol-treated fibers, which agrees well with previous estimates made by different techniques, represents the capacitance of the outer membrane of the fiber. Estimates of the capacitance per unit area of the tubular membrane are made and the significance of the difference between the figures for the capacitance of the surface and tubular membrane is discussed.

scholarly journals Effect of Formaldehyde and Glutaraldehyde on Electrical Properties of Cardiac Purkinje Fibers

1969 ◽  
Vol 53 (5) ◽  
pp. 530-540 ◽  
Author(s):  
H. A. Fozzard ◽  
G. Dominguez
Keyword(s):  
Action Potential ◽  
Negative Charge ◽  
Input Resistance ◽  
Membrane Resistance ◽  
Rapid Loss ◽  
Purkinje Fibers ◽  
Electrophysiological Properties ◽  
Cardiac Purkinje Fibers ◽  
Length Constant ◽  
Upstroke Velocity

The effects of formaldehyde, glutaraldehyde, 1-fluoro-2,4-dinitrobenzene, and 1,5-difluoro-2,4-dinitrobenzene on the electrophysiological properties of cardiac Purkinje fibers were studied. At concentrations of 2.5 mM the aldehydes produced a transient hyperpolarization, lengthening of the plateau of the action potential, and an increase in action potential overshoot and upstroke velocity. If exposure to aldehyde was continued, the fiber failed to repolarize after an action potential and the membrane potential stabilized at about -30 mv. If exposure was terminated before this, recovery was usually complete. At the time the fibers were hyperpolarized the input resistance was increased without much change in length constant, leading to an increase in both calculated membrane resistance and calculated core resistance. Although it was anticipated that an effect of the aldehydes on the membrane was to increase fixed negative charge, it was difficult to explain all the electrophysiological changes on this basis. The major effects of the fluorobenzene compounds were not the same; they produced a shortening of the action potential and a rapid loss of excitability.

Passive properties of the membrane of single freshly isolated smooth muscle cells

1980 ◽  
Vol 239 (5) ◽  
pp. C153-C161 ◽  
Author(s):  
J. J. Singer ◽  
J. V. Walsh
Keyword(s):  
Smooth Muscle ◽  
Smooth Muscle Cells ◽  
Input Resistance ◽  
Muscle Cells ◽  
Membrane Resistance ◽  
Resting Potential ◽  
Stable Steady State ◽  
Membrane Area ◽  
Ion Substitution ◽  
Length Constant

Single, smooth muscle cells were isolated from the stomach muscularis of the toad Bufo marinus and studied on the same day as isolation using standard electrophysiological techniques and direct microscopic observation at high magnification. Following penetration a period of hyperpolarization occurred that appeared to be caused by an increase in K+ conductance activated by Ca2+ entering the cell upon penetration. Ion substitution studies showed that the stable steady-state resting potential was dependent on both [Na+]0 and [K+]0. At [Ca2+]0 = 1.8 mM, active responses could be elicited which, at the higher [Ca2+]0 (< 8mM) generally employed, became action potentials with overshoots. Calculations employing the equations for a short cable and the observed change of membrane potential as a single exponential in response to a small hyperpolarizing current step both indicated that the length constant (lambda) was sufficiently greater than the cell length so that the cell behaved as an isopotential surface during subthreshold perturbations. From photomicrographic measurements of each cell studied and the input resistance, values of specific membrane resistance (Rm) were obtained that ranged as high as 152 k omega x cm2 depending on the ionic environment, most notably on [Ca2+]0. The membrane capacity (Cm) referred to the surface area measured with light microscopy was 1.3 +/- 0.3 microF/cm2 (mean +/- SD). When the best estimate of caveolar membrane area was included, Cm referred to total membrane area (caveolar plus noncaveolar) was approximately 0.8 microF/cm2.

The effect of axotomy on posttetanic potentiation of group Ia synapses in the cat

1986 ◽  
Vol 56 (4) ◽  
pp. 1174-1184 ◽  
Author(s):  
B. Gustafsson ◽  
M. J. Pinter ◽  
H. Wigstrom
Keyword(s):  
Electrical Properties ◽  
High Resistance ◽  
Previous Analysis ◽  
Normal Population ◽  
Input Resistance ◽  
Posttetanic Potentiation ◽  
High Input ◽  
Synaptic Release ◽  
High Input Resistance ◽  
Passive Electrical Properties

Posttetanic potentiation (PTP) of composite Ia excitatory postsynaptic potentials (EPSPs) has been studied in normal cat alpha-motoneurons and in motoneurons axotomized 2-3 wk earlier by ventral root section. The maximal amount of PTP of EPSP amplitude (expressed relative to unpotentiated amplitude) was considerably less in the axotomized population compared with the normal population. The decrease in PTP provoked by axotomy occurs in association with a postaxotomy increase of input resistance, the net effect being that PTP in axotomized cells was much the same as that observed by others in normal motoneurons possessing similarly high input resistance. In agreement with previous results, EPSP peak amplitudes were decreased after axotomy. This decrease seemed to be largely related to an absence of the largest EPSPs, since otherwise the EPSP distributions of normal and axotomized motoneurons showed considerable overlap. It is suggested that the observed decrease in PTP after axotomy is related to a change in synaptic release properties and not secondary to changes in the electrical properties of motoneurons. A previous analysis has suggested that axotomy causes an alteration of the distribution of passive electrical properties among motoneurons such that axotomized cells resemble normal high-resistance motoneurons. The present results suggest that axotomy may affect the distribution of Ia synaptic release properties in a similar manner, since PTP in axotomized motoneurons resembles that observed in normal high-resistance motoneurons.

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