ELECTROPHYSIOLOGY

and The Molecular Basis of Excitability

The Nerve Impulse This is a brief Textbook that covers the basics of the initiation and propagation of the nerve impulse using equivalent circuits with reference to ionic conductances. Voltage dependent conductances are explained on the basis of single channel properties. The text contains links to the simulation programs

[DOWNLOAD pdf FILE](Note: If you get an error, right click on [DOWNLOAD pdf FILE] and click on 'save target as')

Nerve Impulse Laboratory Manual using the new NERVE program

               Simulation Programs

These apps run without Java:

NERVE Interactive solution of the Hodgkin-Huxley equations: voltage clamp, membrane action potential, propagated action potential. Includes circuit with all the currents in the cable model of the axon during propagation. User can change stimulus parameters,ion concentrations, maximum conductances, temperature, add blockers and display all the variables such as conductance or currents. NEW: myelinated nerve.	EXCITABLE MEMBRANE EQUIVALENT CIRCUIT The circuit of a patch of membrane with capacitance, conductances and equilibrium potentials showing currents. 1.Conductances can be interactive. 2. Simulation of passive membrane under current clamp showing  currents. 3. Simulation of active membrane showing currents and conductances (membrane action potential).
DIFFUSION An stochastic simulation of diffusion. User can change container, apply a field or open a channel.	MEMBRANE Stochastic simulation of a membrane with a channel that is permeable to neutral molecule or to a cation. It computes fluxes and when permeable to ions it computes the membrane potential (Nernst potential) User can vary concentration and plot and collect data in a table.
Voltage dependent Potassium Channel A  voltage-gate potassium channel. Basic structure that gives origin to the function. Stochastic simulation of single channel gating currents and single channel ionic currents and the ensemble average of macroscopic gating and ionic currents. User can modify the voltage pattern .	Voltage dependent Sodium Channel An eukaryotic voltage dependent Sodium channel. Basic structure indicating how different domains give origin to the function of the channel. Stochastic simulation of single gating and ionic currents including activation and inactivation and how the macroscopic current is build up from the ensemble average of the single events. User can modify the voltage pattern.
Cable (passive) properties of the axon This program shows the squid giant axon passive properties and how a current stimulus  generate a distribution of membrane potential along the axon. The concepts of time constant and space constant are presented. The user can modify the electrical parameters of the axon and observe the results in the voltage and currents as a function of distance and time.

These apps require Java:

NERVE (Includes Cable simulation of propagated AP)	Cable Properties of the Axon
Equivalent Circuit of The Axon	Model of Shaker K channel gating

Nerve Impulse Laboratory Manual Experiments using the Java NERVE program

Please note: a Java plugin is only required for indicated simulations.

Contact me for comments or questions: fbezanilla@uchicago.edu or francisco.Bezanilla@uv.cl

Thank you for using these programs.

F. Bezanilla

(C) F. Bezanilla, 1998- 2024. Last updated 3/24