MECHANISMS OF IONIC CHANNEL ACTIVITY

Project: Research project

Description

Ion channels are large protein macromolecules which span cell membranes.
They open and close, or gate their pores, controlling the flux of ions
across the membrane, and consequently, membrane potential. The long term
objectives of the proposed research are to determine the gating mechanisms
of ion channels. To work towards this goal, currents will be recorded from
single ion channels with the patch clamp technique and analyzed by
computer. The channels to be studied are the large conductance
calcium-activated potassium channel (BK channel) and the fast Cl channel,
obtained from the membrane of mammalian skeletal muscle cells grown in
tissue culture. Seven specific projects will be carried out: (1) to
determine whether the gating kinetics of ion channels are best described by
models with discrete states and constant transition rates between the
states (Markovian models) or by models with a continuum of states and
fractal scaling (fractal models); (2) to determine whether the brief
interruptions (flickers) commonly observed in currents flowing through
single channels arise from complete or partial channel closures; (3) to
implement an advanced method for determining kinetic gating mechanisms,
which uses all of the non-redundant kinetic information in the single
channel current record and which takes into account both limited time
resolution and the noise in the current record. This method uses computer
simulation to calculate, for a given gating mechanisms, the two-dimensional
distributions of adjacent open and shut interval durations, which are then
compared to the experimental distributions. This advanded method will be
used to determine: (4) the steady-state gating mechanism of the fast Cl
channel; (5) mechanism by which voltage modulates the activity of the fast
Cl channel; (6) the Ca-activated gating mechanism for the normal mode of
the BK channel; and (7) the altered gating mechanisms for the other modes
of the BK channel. In each case, the most likely gating mechanisms will be
defined in terms of kinetic schemes which indicate: the numbers of open
and shut states, the transition pathways between the states, the energy
barriers for the transitions, and how channel activity is modulated through
voltage or calcium induced changes in energy barrier heights. Characterizing ion channels is an important step towards understanding the
molecular basis of both normal muscle function and those muscle diseases
where defects in the numbers and/or functions of ion channels are
implicated. Once the normal channels are characterized, it will be
possible to determine if their numbers and/or functions are altered in the
disease states.
StatusFinished
Effective start/end date9/1/838/31/14

Funding

  • National Institutes of Health: $367,388.00
  • National Institutes of Health: $213,724.00
  • National Institutes of Health: $286,967.00
  • National Institutes of Health: $336,600.00
  • National Institutes of Health
  • National Institutes of Health: $319,905.00
  • National Institutes of Health: $177,485.00
  • National Institutes of Health: $197,904.00
  • National Institutes of Health
  • National Institutes of Health: $336,600.00
  • National Institutes of Health
  • National Institutes of Health: $191,771.00
  • National Institutes of Health
  • National Institutes of Health: $282,779.00
  • National Institutes of Health: $319,905.00
  • National Institutes of Health
  • National Institutes of Health: $333,234.00
  • National Institutes of Health
  • National Institutes of Health: $365,489.00
  • National Institutes of Health: $283,061.00
  • National Institutes of Health: $367,388.00
  • National Institutes of Health
  • National Institutes of Health
  • National Institutes of Health
  • National Institutes of Health: $331,015.00
  • National Institutes of Health: $293,100.00
  • National Institutes of Health: $321,416.00

Fingerprint

Ion Channels
Large-Conductance Calcium-Activated Potassium Channels
Channelopathies
Ions
Physiological Phenomena
muscles
kinetics
Calcium-Activated Potassium Channels
HEK293 Cells
Cell Membrane
membranes
Muscles
Patch-Clamp Techniques
Xenopus
Neurons
Oocytes
Membrane Potentials
Muscle Cells
Muscle Contraction
fractals

ASJC

  • Medicine(all)