Single-Channel Studies of TTX-Sensitive and TTX-Resistant Sodium Channels in Developing Rat Muscle Reveal Different Open Channel Properties

1986 ◽  
Vol 479 (1 Tetrodotoxin,) ◽  
pp. 152-161 ◽  
Author(s):  
RICHARD E. WEISS ◽  
RICHARD HORN
Keyword(s):  
Sodium Channels ◽  
Open Channel ◽  
Single Channel ◽  
Rat Muscle ◽  
Developing Rat ◽  
Channel Properties

scholarly journals Modeling Macroscopic Currents of Ion Channels

2021 ◽  
Author(s):  
Di Wu
Keyword(s):  
Open Channel ◽  
Single Channel ◽  
Ion Permeation ◽  
Model Studies ◽  
Proposed Model ◽  
Current Voltage ◽  
Improved Model ◽  
Boltzmann Model ◽  
Channel Properties ◽  
Current Voltage Relation

Ion-channel functions are often studied by the current-voltage relation, which is commonly fitted by the Boltzmann equation, a powerful model widely used nowadays. However, the Boltzmann model is restricted to a two-state ion-permeation process. Here we present an improved model that comprises a flexible number of states and incorporates both the single-channel conductance and the open-channel probability. Employing the channel properties derived from the single-channel recording experiments, the proposed model is able to describe various current-voltage relations, especially the reversal ion-permeation curves showing the inward- and outward-rectifications. We demonstrate the applicability of the proposed model using the published patch-clamp data of BK and MthK potassium channels, and discuss the similarity of the two channels based on the model studies.

scholarly journals Renal sodium channels: Regulation and single channel properties

1995 ◽  
Vol 48 (4) ◽  
pp. 941-949 ◽  
Author(s):  
Douglas C. Eaton ◽  
Andrea Becchetti ◽  
Heping Ma ◽  
Brian N. Ling
Keyword(s):  
Sodium Channels ◽  
Single Channel ◽  
Channel Properties

scholarly journals Reconstitution of the ATP-sensitive potassium channel of skeletal muscle. Activation by a G protein-dependent process.

1989 ◽  
Vol 94 (3) ◽  
pp. 445-463 ◽  
Author(s):  
L Parent ◽  
R Coronado
Keyword(s):  
Skeletal Muscle ◽  
G Protein ◽  
Muscle Activation ◽  
Open Channel ◽  
Single Channel ◽  
Rabbit Skeletal Muscle ◽  
S 100 ◽  
Internal Side ◽  
Gamma S ◽  
Channel Properties

Potassium channels inhibited by adenosine-5'-trisphosphate, K(ATP), found in the transverse tubular membrane of rabbit skeletal muscle were studied using the planar bilayer recording technique. In addition to the single-channel properties of K(ATP) we report its regulation of Mg2+ and by the guanosine-5'-trisphosphate analogue, GTP-y(gamma)-S. The K(ATP) channel (a) has a conductance of 67 pS in 250 mM internal, 50 mM external KCl, and rectifies weakly at holding potentials more positive than 50 mV, (b) is not activated by internal Ca2+ or membrane depolarization, (c) has a permeability ratio PK/PNa greater than 50, and (d) is inhibited by millimolar internal ATP. Activity of K(ATP), measured as open channel probability as a function of time, was unstable at all holding potentials and decreases continuously within a few minutes after a recording is initiated. After a decrease in activity, GTP-y-S (100 microM) added to the internal side reactivated K(ATP) channels but only transiently. In the presence of internal 1 mM Mg2+, GTP-y-S produced a sustained reactivation lasting 20-45 min. Incubation of purified t-tubule vesicles with AlF4 increased the activity of K(ATP) channels, mimicking the effect of GTP-y-S. The effect of AlF4 and the requirement of GTP-y-S plus Mg2+ for sustained channel activation suggests that a nucleotide-binding G protein regulates ATP-sensitive K channels in the t-tuble membrane of rabbit skeletal muscle.

Sodium current and membrane potential in EDL muscle fibers from normal and dystrophic (mdx) mice

1991 ◽  
Vol 261 (4) ◽  
pp. C718-C725 ◽  
Author(s):  
C. Mathes ◽  
F. Bezanilla ◽  
R. E. Weiss
Keyword(s):  
Membrane Potential ◽  
Sodium Channels ◽  
Single Channel ◽  
Muscle Fibers ◽  
Mdx Mice ◽  
Apparent Difference ◽  
Sodium Currents ◽  
Edl Muscle ◽  
Single Channel Currents ◽  
Channel Properties

The macroscopic and single-channel properties of sodium currents and membrane potential were studied in intact extensor digitorum longus (EDL) muscle fibers from mdx (C57BL/10ScSn-mdx) and normal (C57BL/10SnJ) mice. The voltage dependence of activation and inactivation were determined and the associated gating charges were calculated to determine if the lack of dystrophin associated with the mdx condition has any influence on sodium channels either directly or by effects on the membrane environment of the channel. Sodium currents were recorded from cell-attached patches on EDL muscle fibers isolated by collagenase treatment and manual dissection. Both macroscopic and single-channel currents were studied. We found no apparent difference in the sodium channel properties from the two types of muscle. In addition, microelectrode measurements in both mdx and normal muscle fibers indicated similar resting membrane potentials (Vm around -95 mV), which suggests that the normal behavior of sodium channels in the muscle sarcolemma is unaffected by the X-linked gene defect.

Expression of NMDA channels on cerebellar Purkinje cells acutely dissociated from newborn rats

1992 ◽  
Vol 68 (5) ◽  
pp. 1901-1905 ◽  
Author(s):  
C. Rosenmund ◽  
P. Legendre ◽  
G. L. Westbrook
Keyword(s):  
Nmda Receptors ◽  
Purkinje Cells ◽  
Developmental Plasticity ◽  
Open Channel ◽  
Single Channel ◽  
Newborn Rats ◽  
Conflicting Evidence ◽  
Nmda Channels ◽  
Cerebellar Purkinje Cells ◽  
Channel Properties

1. Conflicting evidence exists concerning the expression and properties of N-methyl-D-aspartate (NMDA) receptors on cerebellar Purkinje cells during development. We used whole-cell and single-channel recording to examine NMDA receptors on acutely dissociated Purkinje cells from newborn rats (postnatal day 0-4). 2. NMDA channels were present on > 80% of identified Purkinje cells and had pharmacological and single-channel properties that were indistinguishable from NMDA receptors on other neurons. In particular, responses were glycine-dependent and Mg2+ produced flickery open-channel block. 3. Our results demonstrate the transient expression of NMDA receptor/channels on Purkinje cells early in development. As NMDA receptors have been implicated in developmental plasticity in other regions of the CNS, a similar role is feasible during climbing fiber innervation of Purkinje cells.

Sign in / Sign up

Export Citation Format

Share Document