Membrane potential simulation program for IBM-PC-compatible equipment for physiology and biology students.

MEMPOT is an interactive graphic simulation program, written in Turbo C for IBM-PC-compatible equipment and designed to teach students in the physiological and biological sciences about the measurement and ion dependence of cell membrane potentials. Different external salt solution values can be chosen and an intracellular electrode can be moved on the screen to impale one of a group of cells and measure resting or action potential responses. A simulated voltage-to-frequency audio signal emulates normal experimental audio monitoring of the electrode potential, and a window displays a simulated oscilloscope trace (together with "electrical noise") of the resting or action potential response. The average value of each set of successful impalements is determined for each solution. Once measurements have been made over a suitable range of different solutions, the data can be reentered and plotted graphically on the screen and an interactive approach can be used to determine relative sodium-to-potassium permeabilities at rest or at the action-potential peak. A randomization routine varies permeability ratios within a small range between runs.