ALTERATIONS IN ACTION POTENTIAL PROPAGATION

A. Local Anesthetics; e.g. lidocaine, procaine (Novacain)

Action: block regenerative Na channels and thus prevent generation or propagation of action potentials

B. Interstitial Potassium Ion Concentration

Action: alters the resting potential and thus the amount of depolarization necessary to reach threshold; e.g. reduced excitability of hypokalemia

C. Demylination Diseases

1. Examples: CNS – Multiple Sclerosis; PNS – Guillian-Barre syndrome

2. Consequence: initially slow conduction, eventually block conduction altogether