Why does conduction velocity decrease when the nerve is treated with procaine?

Procaine is a local anesthetic that blocks sodium channels in nerve fibers, preventing the influx of sodium ions necessary for depolarization during action potentials. When these channels are inhibited, the ability of the nerve to propagate electrical signals is reduced, leading to a decrease in conduction velocity. Additionally, procaine can increase the threshold for action potential generation, further slowing nerve conduction. Overall, the effect of procaine on sodium channel activity directly impacts the speed at which nerve impulses travel.