Positive sharp wave and fibrillation potential modeling

A finite muscle fiber simulation program which calculates the extracellular potential for any given intracellular action potential (IAP) was used to m odel a fibrillation potential and a positive sharp wave. This computer mode l employs the core conductor model assumptions for an active muscle fiber a nd allows two distinct types of end effects: a cut or a crush. A "cut end" is defined as a membrane segment with the termination of both active and pa ssive ion channels. The "crush end" is simulated as a focal membrane segmen t which blocks action potential propagation, and is connected to a region o f normal membrane on either side of it so that a normal transmembrane poten tial is maintained beyond the crush zone. A prototypical positive sharp wav e of appropriate amplitude and duration could only be detected extracellula rly by using an IAP of the configuration found in denervated rat muscle rec orded from a muscle fiber terminating in a crush segment of membrane. (C) 1 999 John Wiley & Sons, Inc.