Squid Axon

Producer: Sheffield BioScience Programs

This interactive program simulates a number of experiments which may be performed on the isolated giant axon of the squid to investigate the biophysical properties of nerve. The Methods section uses a combination of text and high-resolution colour graphics to describe the preparation, the apparatus used to record the resting potential of the axon and the techniques of current and voltage clamping. The Experiments section is highly interactive and may be used to investigate: the resting potential (where students may vary the concentrations of Na+, K+ and Cl– in the extracellular fluid [ECF] and axoplasm, then record changes in the resting membrane potential) and the action potential (where students may design experimental protocols which allow them to perform current clamp and voltage clamp experiments). With current clamp experiments the ECF concentrations of Na+, K+ and Cl– may be varied individually and single or paired stimuli applied; records of voltage or conductance changes are then displayed. With voltage clamp experiments the student may set a membrane holding potential and up to 3 command potentials to voltage clamp the axon and record membrane current or conductance changes. The intracellular fluid [ICF] and ECF concentrations of Na+, and ICF K+ may be changed and the action of tetrodotoxin and tetraethylammonium investigated. Results are derived from widely accepted algorithms (Goldman-Hodgkin-Katz, Hodgkin & Huxley models) and displayed on a simulated oscilloscope screen from which students are able to take accurate measurements.


Medium: 3.5" disk; CD-ROM System requirements: MS-DOS Price: £120.00 (departmental multiuser/network licence; includes documentation - program manual and, where appropriate, student’s workbook and tutor’s notes - and postage)