MECHANISMS OF IONIC CHANNEL ACTIVITY

Project: Research project

Description

The overall purpose of this research proposal is to determine the
properties and underlying kinetic mechanisms of two different ionic
channels in cell membranes: the calcium-activated potassium channel and a
voltage dependent chloride channel of large conductance. Currents that
flow through single ionic channels in the sarcolemma of cultured rat
skeletal muscle cells will be recorded under voltage clamp using the patch
clamp technique. With this electrophysiological technique it is possible
to study the kinetics of single channels by observing (through step changes
in the current) when single channels open and close. The effects of Na, K,
and Mg ions, step changes in [Ca] ion, and possible phosphorylation on the
activity of the Ca-activated K channel will be characterized. The
mechanism underlying the observation that openings of the Ca-activated K
channel tend to occur in bursts will also be examined. The effect of
membrane potential on activation, inactivation, and removal of inactivation
for the voltage dependent C1 channel of large conduictance will also be
characteized, as well as the permeability of this channelto various ions.
The above data will be used to obtain information about the number of open
and closed states, the mean lifetimes of the open and closed states, and
the rate constants for transitions between the various states for each
channel. These findings will then be used to develop a kinetic scheme for
each channel. The Ca-activated K channel modulates repetitive firing in
neurons and affects membrane potential and excitability in muscle. The C1
channel of large conductance would also affect membrane excitability. To
understand the properties and function of nerve and muscle membranes, it
will be necessary to understand the properties and mechanisms of these two
channels. Understanding these channels may also help in understanding and
treating nerve and muscle disease, as therapeutic agents and toxins often
exert their specific effects on ionic channels in cell membranes.
StatusFinished
Effective start/end date9/1/838/31/88

Funding

  • National Institutes of Health

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Ion Channels
Ions
Muscles
Cell Membrane
Calcium-Activated Potassium Channels
Sarcolemma
Chloride Channels
Membranes
Membrane Potentials
Muscle Cells
Permeability
Research Design
Phosphorylation
Therapeutics

ASJC

  • Medicine(all)