Measurement of passive membrane parameters with whole-cell recording from neurons in the intact amphibian retina

1989 ◽  
Vol 61 (1) ◽  
pp. 218-230 ◽  
Author(s):  
P. A. Coleman ◽  
R. F. Miller
Keyword(s):  
Time Constant ◽  
Ganglion Cells ◽  
Dendritic Tree ◽  
Input Resistance ◽  
Membrane Resistance ◽  
Retinal Neurons ◽  
Whole Cell ◽  
Cell Recording ◽  
Tryptic Activity ◽  
Specific Membrane

1. Whole-cell recordings have been obtained from intact, photoactive retinal neurons using patch-clamp electrodes in the amphibian superfused retina eyecup preparation. 2. After removal of the vitreous humor from the surface of the retina, using a collagenase with low tryptic activity, high-resistance seals (1-10 G omega) could be formed between the patch pipette and the cell membrane by applying mild suction to the pipette. Additional suction broke the membrane patch and provided continuity between the low-resistance pipette and the interior of the neuron. 3. Measurements of input resistance and time constant were obtained from bipolar, amacrine, and ganglion cells. Assuming the membrane capacitance was 1 microF/cm2, time constant data were used to derive the specific membrane resistance. The average specific membrane resistance for the inner retinal neurons in our sample was 68,000 omega.cm2. 4. Analysis of the charging curve induced by a brief current pulse applied to the soma was used to analyze the average electrotonic length of dendrites. The charging curves of some ganglion cells were well represented by a single exponential, suggesting that they were essentially isopotential. 5. The voltage decay along an equivalent cylinder model of a ganglion cell was calculated, using the experimentally obtained values of membrane resistance to compute decay of steady-state voltages along the dendritic tree. The calculations indicate that with the high membrane resistance values implied by this study, the electrotonic length of dendritic cables were short, and there may be relatively little attenuation of the synaptic potentials irrespective of their location along the dendritic tree.

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.

Dendritic integration in ganglion cells of the mudpuppy retina

1995 ◽  
Vol 12 (1) ◽  
pp. 165-175 ◽  
Author(s):  
T.J. Velte ◽  
R.F. Miller
Keyword(s):  
Functional Organization ◽  
Simulation Analysis ◽  
Ganglion Cells ◽  
Impedance Matching ◽  
Dendritic Tree ◽  
Membrane Resistance ◽  
Transient Responses ◽  
Dendritic Integration ◽  
Necturus Maculosus ◽  
Integration Efficiency

AbstractComputer simulations were carried out to evaluate the influence of varying the membrane resistance (Rm) on the dendritic integration capacity of three classes of ganglion cells in the mudpuppy (Necturus maculosus) retina. Three broadly different morphological classes of ganglion cells were selected for this study and represent the range of dendritic tree sizes found in the ganglion cell population of this species. Simulations were conducted on anatomical data obtained from cells stained with horseradish peroxidase; each cell was traced, using a computer as an entry device and later converted to a compartmental (electrical) representation of the cell. Computer-simulation analysis used a time-variant conductance change which was similar in waveform to light-activated bipolar cell input. The simulated membrane resistance for each cell varied between 5000 and 100,000 Ω cm2, and conductance changes were introduced into different regions of the soma-dendritic tree to evaluate dendritic integration efficiency. When higher values of Rm are used, even the largest cells become electrotonically compact and attenuation of voltage responses is minimized from distal to soma regions. Responses were less attenuated from proximal to distal regions of the cell because of the favorable impedance matching, and because less current is required to polarize small “sealed” dendritic terminations. Steady-state responses integrate more effectively than transient responses, particularly when Rm is high, since transient responses were more attenuated by the membrane capacitance. The possibility that Rm is a dynamic property of retinal ganglion cells is discussed in view of the functional organization of dendritic integration efficiency as Rm fluctuates from low to high values.

Enhancement of Whole Cell Synaptic Currents by Low Osmolarity and by Low [NaCl] in Rat Hippocampal Slices

1997 ◽  
Vol 77 (5) ◽  
pp. 2349-2359 ◽  
Author(s):  
Rong Huang ◽  
Daniel F. Bossut ◽  
George G. Somjen
Keyword(s):  
Synaptic Transmission ◽  
Time Constant ◽  
Hippocampal Slices ◽  
Input Resistance ◽  
Tissue Slices ◽  
Synaptic Currents ◽  
Whole Cell ◽  
Input Capacitance ◽  
Postsynaptic Currents ◽  
Inward Currents

Huang, Rong, Daniel F. Bossut, and George G. Somjen. Enhancement of whole cell synaptic currents by low osmolarity and by low [NaCl] in rat hippocampal slices. J. Neurophysiol. 77: 2349–2359, 1997. We recorded whole cell currents of patch-clamped neurons in stratum pyramidale of CA1 region of rat hippocampal tissue slices. Synaptic currents were evoked by orthodromic stimulation while holding potential of the neuron was varied from hyperpolarized to depolarized levels. Extracellular osmolarity (πo) was lowered by superfusion with artificial cerebrospinal fluid in which NaCl concentration ([NaCl]) was reduced. The effect of low extracellular NaCl was tested in additional trials in which NaCl was substituted by isosmolar fructose. Both lowering of πo and isosmotic lowering of extracellular [NaCl] ([NaCl]o) caused reversible increase of excitatory postsynaptic currents. The effect of lowering πo was concentration dependent, and it was significantly stronger than the effect of equivalent isosmotic lowering of [NaCl]o. Inhibitory postsynaptic currents also increased in many but not in all cases. Lowering of πo caused a prolongation of the time constant of relaxation of the capacitive charging current induced by small hyperpolarizing voltage steps. A virtual input capacitance, calculated by dividing this time constant by the input resistance, increased during hypotonic exposure. Isosmotic lowering of [NaCl]o had no effect on time constant or input capacitance. Depolarizing voltage commands evoked spikelike inward currents presumably representing Na+-dependent action potentials generated outside the voltage-clamped region of the cell. These current spikes became smaller in low πo and in low [NaCl]o. Broader, voltage-dependent, presumably Ca2+-mediated inward currents became more prominent during hypotonic exposure. We conclude that lowering of [NaCl]o causes enhancement of excitatory synaptic transmission. Transmission may be facilitated by the uptake of Ca2+ into presynaptic terminals as well as into postsynaptic target neurons, induced by the low [NaCl]o. Lowering of πo enhances synaptic transmission more than does a corresponding isosmotic lowering of [NaCl]. The excess increase recorded from the cell soma in low πo may in part be due to changing electrotonic length caused by the swelling of dendrites.

scholarly journals Chemosensory responses in isolated olfactory receptor neurons from Necturus maculosus.

1992 ◽  
Vol 99 (3) ◽  
pp. 415-433 ◽  
Author(s):  
V E Dionne
Keyword(s):  
Olfactory Receptor ◽  
Membrane Conductance ◽  
Input Resistance ◽  
Primary Response ◽  
Olfactory Receptor Neurons ◽  
Whole Cell ◽  
Whole Cell Recording ◽  
Necturus Maculosus ◽  
Cell Recording ◽  
Receptor Neurons

Olfactory receptor neurons were isolated without enzymes from the mudpuppy, Necturus maculosus, and tested for chemosensitivity. The cells responded to odorants with changes in firing frequency and alterations in excitability that were detected with tight-seal patch electrodes using on-cell and whole-cell recording conditions. Chemosensitive cells exhibited two primary response characteristics: excitation and inhibition. Both types of primary response were observed in different cells stimulated by mixtures of amino acids as well as by the single compound L-alanine, suggesting that there may be more than one transduction pathway for some odorants. Using the normal whole-cell recording method, the chemosensitivity of competent cells washed out rapidly; a resistive whole-cell method was used to record odorant responses under current-clamp conditions. In response to chemical stimulation, excitability appeared to be modulated in several different ways in different cells: odorants induced hyperpolarizing or depolarizing receptor potentials, elicited or inhibited transient, rhythmic generator potentials, and altered excitability without changing the membrane potential or input resistance. These effects suggest that olfactory transduction is mediated through at least three different pathways with effects on four or more components of the membrane conductance. Polychotomous pathways such as these may be important for odor discrimination and for sharpening the "odor image" generated in the olfactory epithelium.

Cable properties of layer V neurons from cat sensorimotor cortex in vitro

1984 ◽  
Vol 52 (2) ◽  
pp. 278-289 ◽  
Author(s):  
C. E. Stafstrom ◽  
P. C. Schwindt ◽  
W. E. Crill
Keyword(s):  
Voltage Clamp ◽  
Time Constant ◽  
Neuron Model ◽  
Membrane Resistance ◽  
Resting Potential ◽  
Voltage Range ◽  
Cable Properties ◽  
Layer V ◽  
Specific Membrane

The passive cable properties of neurons from layer V of cat neocortex were studied in an in vitro slice preparation using current-clamp techniques and a single-microelectrode voltage clamp. Neurons were examined in the presence and absence of several agents that block time- and voltage-dependent conductances. The charging response to an injected current pulse was well fitted by a single exponential in 12 of 17 cells examined. By itself, this result would suggest that most of the neurons are isopotential. However, the existence of a nonisopotential region was demonstrated in all neurons examined using two alternative, independent methods: application of voltage-clamp steps and current impulses. The decay of the capacitive charging transient following a voltage-clamp step reflects charge redistribution solely in the nonisopotential region and had a mean time constant about 17% of the membrane time constant, tau m. The voltage decay following a current impulse was always fitted by (at least) two exponentials, the shorter of which was about 9% of tau m. These results suggest that a nonisopotential region exists but is electrotonically short, of relatively low-input conductance, or both, independent of a particular neuron model. Adopting Rall's (23, 24) idealized neuron model (isopotential compartment attached to a finite-length uniform cable) resulted in a mean value for the equivalent electrotonic length (L) of the nonisopotential compartment of 0.72 space constants from voltage-clamp data and 1.21 space constants from impulse-response data. A dendrite-to-soma conductance ratio (p) of 2-4 was obtained from either procedure. There were no significant differences in the cable parameters between normal cells and those where conductance-blocking agents were present. A specific membrane resistance (Rm) ranging from 2,300 to 11,700 omega X cm2 was estimated by assuming values of specific membrane capacitance reported in the literature. We conclude that large layer V neocortical neurons in vitro are electrotonically compact in the voltage range near resting potential and in the absence of significant tonic synaptic input. In this respect, their electrotonic cable properties resemble those of other mammalian neurons in vitro.

Reduced ionic conductance in turtle brain

1993 ◽  
Vol 265 (4) ◽  
pp. R929-R933 ◽  
Author(s):  
C. J. Doll ◽  
P. W. Hochachka ◽  
P. B. Reiner
Keyword(s):  
Statistical Difference ◽  
Pyramidal Neurons ◽  
Control Measures ◽  
Ion Pump ◽  
Ionic Conductance ◽  
Whole Cell ◽  
Pump Activity ◽  
Cell Recording ◽  
Normoxic Control ◽  
Specific Membrane

Whole cell recording techniques were employed to measure whole cell (Gw) and specific membrane (Gm) conductance in turtle and rat pyramidal neurons in slices. Results indicate that rat neurons are 4.2 times more conductive compared with turtle neurons at 25 degrees C, which is accentuated by temperature, so that rat neurons at 37 degrees C are 22 times more conductive than turtle neurons at 15 degrees C. A conductance Q10 of 1.9 was measured for both turtle (15-25 degrees C) and rat (25-35 degrees C) pyramidal neurons. Conductance measurements of turtle pyramidal neurons over 6-9 h of anoxia indicate no statistical difference between Gm or Gw from normoxic control measures. These results indirectly support the concept of low ATP-dependent ion pump activity in the turtle brain as one mechanism for reduced energy expenditure in the normoxic state.

GABA-activated single channel currents in outside-out membrane patches from rat retinal ganglion cells

1989 ◽  
Vol 3 (3) ◽  
pp. 275-279 ◽  
Author(s):  
Stuart A. Lipton
Keyword(s):  
Retinal Ganglion Cells ◽  
Cortical Neurons ◽  
Single Channel ◽  
Ganglion Cells ◽  
Retinal Ganglion ◽  
Whole Cell ◽  
Cell Recording ◽  
Excised Patches ◽  
Patch Configuration ◽  
Single Channel Currents

Abstractγ-aminobutyric acid (GABA) evokes large whole-cell currents in solitary mammalian retinal ganglion cells studied by the patch-clamp method. This evidence suggests that GABA acts directly on the retinal ganglion cells as an inhibitory transmitter as it does elsewhere in the mammalian central nervous system. Here, single-channel recordings of the currents underlying the GABA-induced responses were studied in outside-out patches of cell membrane. In some other preparations, single GABAA channels recorded in the excised patch configuration have been shown to have altered properties in comparison to responses elicited during whole-cell recording. For example, in cortical neurons single GABA-activated channels in excised patches display accelerated desensitization kinetics as well as rapid rundown of the response. Therefore, in retinal ganglion cells, responses generated by GABA in cell-free patches were compared to whole-cell responses. After determining that the responses to GABA in acutely isolated outside-out patches were indeed similar to those of the whole-cell currents in retinal ganglion cells, the unitary conductances were studied. It was determined that these single-channel events resemble those reported in other nervous tissues with 4 elementary conductances of ~10 pS, 19–22 pS, 30–33 pS, and 45–50 pS at 33–35°C.

Electrotonic parameters of rat dentate granule cells measured using short current pulses and HRP staining

1983 ◽  
Vol 50 (5) ◽  
pp. 1080-1097 ◽  
Author(s):  
D. Durand ◽  
P. L. Carlen ◽  
N. Gurevich ◽  
A. Ho ◽  
H. Kunov
Keyword(s):  
Time Constant ◽  
Granule Cells ◽  
Short Pulse ◽  
Dendritic Tree ◽  
Input Resistance ◽  
Synaptic Activity ◽  
Branch Points ◽  
Pulse Technique ◽  
Current Pulses ◽  
Branching Points

The passive electrotonic parameters of nerve cells in the dentate gyrus of the rat were studied in vitro. Intracellular recordings from 30 granule cells and 3 pyramidal basket cells followed by intracellular injection of horseradish peroxidase (HRP), allowed calculations of input resistance (RN), membrane time constant (tau m), electrotonic length (L), ratio of dendritic to somatic conductance (rho), membrane specific capacitance and resistance (Rm, Cm), and specific axoplasmic resistance (Ri). The analysis of the voltage decays from long saturating (100 ms) and short (0.5 ms) current pulses showed that the short-pulse method gave better resolution for the measurement of the time constants and avoided some of the time-dependent nonlinearities but required larger currents than the long pulse. Morphological analysis of 49 branching points taken from the dendritic trees of granule cells showed that the branching power, n, is equal to 1.56 +/- 0.186 and was fairly constant throughout the tree. Given the fact that all dendrites have approximately the same length and number of branch points, the granule cell dendritic tree can be meaningfully collapsed into an equivalent cable. Moreover, electrophysiological data suggested that the cable had a "sealed" end or at least a high-impedance termination. Based on an equivalent cable model with a sealed end and a lumped soma impedance, a method was implemented to analyze the multiexponential decays from hyperpolarizing current pulses and to solve the equations of the model. This was done successfully in only 40% of the cells and yielded the following mean values for L = 1.13 and rho = 7.58. From the measurements of the soma surface area (S) and the equivalent cable diameter (D), the average specific membrane parameters were calculated: Rm = 2,726 alpha x cm2, Cm = 5.24 microF/cm2, Ri = 101 alpha x cm. The input resistance and time constant of the granule cells as measured from the short-pulse technique averaged to RN 58.57 M alpha and tau m = 16.21 ms. The failure of the model to fit 60% of the cells was interpreted to be due to the presence of a somatic shunt resulting from electrode injury, tonic synaptic activity, a lower somatic membrane specific resistance, or electronic coupling.(ABSTRACT TRUNCATED AT 400 WORDS)

Electrotonic architecture of cat gamma motoneurons

1994 ◽  
Vol 72 (5) ◽  
pp. 2302-2316 ◽  
Author(s):  
R. E. Burke ◽  
R. E. Fyffe ◽  
A. K. Moschovakis
Keyword(s):  
Steady State ◽  
Attenuation Factor ◽  
Input Resistance ◽  
Membrane Resistance ◽  
Morphological Data ◽  
Membrane Area ◽  
Current Pulses ◽  
Specific Membrane ◽  
Best Fit ◽  
Calculated Average

1. Experimental measures of input resistance, RN, and responses to brief hyperpolarizing current pulses were obtained in identified gamma-motoneurons in pentobarbital-anesthetized cats using conventional sharp micropipettes. The same cells were subsequently injected with horseradish peroxidase and completely reconstructed. In two cells, the electrophysiological and morphological data were of sufficient quality to permit estimation of specific membrane resistance, Rm, using biologically plausible ranges of specific cytoplasmic resistance, Ri, and membrane capacitance, Cm. 2. A combination of steady-state and dynamic computer models were employed to reconcile cell morphology with RN and the trajectories of the voltage decay following brief current pulses delivered to the soma. Simulated transient responses matched the tails of the observed transient when generated with the same current injections used experimentally. With Cm < or = 1.0 microF cm-2, the most satisfactory fits were obtained when the values of Rm assigned to the soma, Rms, were much smaller than the spatially uniform value assigned to the dendrites, Rmd and Ri = 60–70 omega cm. With Cm = 1.0 microF cm-2, Rms ranged from 260 to 427 omega cm2, whereas Rmd was approximately 33 K omega cm2. With Cm = 0.8 microF cm-2, Rms ranged from 235 to 357 omega cm2 and Rmd was between 62 and 68 K omega cm2. When Rm was constrained to be spatially uniform (i.e., Rm = Rms), implausibly high values of Cm (2.5–5.0 microF cm-2; Ri = 70 omega cm) were required to match the observed tail time constant, tau o,peel, but the simulated transients did not otherwise match those obtained experimentally. 3. With best fit values of Rms and Rmd, both gamma-motoneurons were electronically relatively compact (80% of total membrane area within 0.85 length constants from the soma). However, the calculated average steady-state inward attenuation factor (AFin) for voltages generated at any point within the dendrites increased rapidly with distance from the soma, reaching levels of < or = 90 and < or = 45 for the proximal 80% of membrane area for the respective motoneurons in the presence of a somatic shunt (Rms ≪ Rmd). If we assume that the somatic shunt is an artifact of sharp micropipette penetration (i.e., that Rms = Rmd for uninjured cells), then AFin decreased to < or = 20 and < or = 15, respectively, for the proximal 80% of cell membrane.(ABSTRACT TRUNCATED AT 400 WORDS)

Whole-cell recording of anoxic effects on hippocampal neurons in slices

1993 ◽  
Vol 69 (1) ◽  
pp. 118-127 ◽  
Author(s):  
L. Zhang ◽  
K. Krnjevic
Keyword(s):  
Hippocampal Neurons ◽  
Input Resistance ◽  
Sprague Dawley ◽  
Whole Cell ◽  
Potassium Gluconate ◽  
Whole Cell Recording ◽  
Sprague Dawley Rats ◽  
Pyramidal Layer ◽  
Cell Recording ◽  
A Minor

1. In 400-microns-thick slices from young adult Sprague-Dawley rats, CA1 pyramidal layer neurons were studied by the whole-cell recording technique. The patch pipettes were filled most often with (in mM) 140 potassium gluconate, 2 MgCl2, and 0.2 guanosine triphosphate (GTP): in many cases, 2 mM ATP and/or 1.1 mM EGTA and 0.1 mM Ca were added. The slices were kept at 30–32 degrees C. 2. Cells recorded with ATP-containing electrodes had a much higher input resistance (RN, 101 +/- 5.6 M omega, mean +/- SE) and somewhat less negative resting potentials (Vm; -59.8 +/- 1.1 mV) than cells recorded with ATP-free electrodes (71 +/- 2.7 M omega and -63.1 +/- 0.8 mV). The presence or absence of ethylene glycol-bis(beta-aminoethyl ether)-N,N,N',N'-tetraacetic acid (EGTA) or the substitution of KCl for potassium gluconate did not significantly affect Vm or RN. 3. Overall changes in Vm and RN elicited by anoxia (95% N2-5% CO2 for 3–6 min) were much less pronounced than those seen previously with intracellular electrodes: instead of a hyperpolarization and a approximately 50% fall in RN, there was only a minor depolarization (by 2.4 +/- 0.7 mV) and a small reduction in RN (by 12 +/- 2.4%). During voltage clamp, at holding potentials approximately -35 mV, anoxia evoked only very small outward currents, especially when we recorded with ATP-containing electrodes. 4. The remaining anoxic changes in RN (but not Vm) were very significantly smaller (P < 0.001) when recorded with ATP-containing electrodes (-6 +/- 1.4%) than with ATP-free electrodes (-19 +/- 2.7%). The presence of internal EGTA (1.1-11 mM) was associated with significantly smaller (P < 0.05) anoxic changes in RN: -9.7 +/- 2.0% versus -17 +/- 3.1% in its absence. EGTA also reduced slow afterhyperpolarizations by 80%, though even 11 mM EGTA did not abolish them. However, EGTA had no significant effect on anoxic changes in Vm and did not suppress voltage sags observed during applications of hyperpolarizing current pulses. 5. Judging by these observations, it appears that 1) the much greater anoxic changes in Vm and RN recorded with intracellular electrodes are probably mediated by a diffusible cytosolic agent and 2) during whole-cell recording, both resting RN and the anoxic fall in RN are more strongly determined by cytosolic [ATP] than [Ca]. How ATP affects RN and anoxic changes in RN remains to be established.

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