A. Strassberg
Caltech
April 1992
(VClamp.doc)

VClamp Demo
- this GENESIS script simulates the response of a voltage- and space-
clamped patch of squid giant axon membrane to a step change in
membrane voltage.
- the membrane consists of a population of Na and K channels
channels undergoing Markov kinetics with voltage-dependent
rate constants.  The Na and K channel population objects are
demonstrated.  A Voltage clamp is applied to the membrane and
the dynamics of the total ionic conductances gNa and gK can be
observed for step changes in the membrane voltage.

I. Installment
- the entire script for the VClamp demo is contained within the
file <VClamp.g>.

II. Units
                time            ms
                voltage         mV
                area            um2
                conductance     pS
                density         channels/um^2

III. Simulation Operation
- for given membrane surface area, Na and K channel densities,
Na and K open channel conductances, initial holding membrane
voltage, and final holding membrane voltage after the voltage
step, the simulation computes the behavior of the total membrane
conductances to Na and to K, gNa(t) and gK(t) respectively.
- note: The voltage step occurs at 5 ms, which is preset within the
script code.  The specific Na and K voltage-dependent probabilities
also are preset within the script code.

IV. See Also

        NaChannel.doc
        KChannel.doc
        UnClamp.doc
        ConClamp.doc
        ConVClamp.doc

        Strassberg and DeFelice, 1992, Neural Computation (submitted)
        Strassberg and DeFelice, 1992, CNS Memo

V.  Questions

        Please send any questions to
        strass@cns.caltech.edu

