Effects of Ca2 and K channel blockers on nerve impulses recorded from guinea‐pig postganglionic sympathetic nerve terminals.

Abstract

1. A focal extracellular suction electrode was used to investigate the contributions of K+ and Ca2+ currents to the nerve impulse recorded from sympathetic nerve terminals innervating the guinea‐pig vas deferens in vitro. 2. Perfusing the electrode with Cd2+ (0.1‐0.5 mM) had little effect on the configuration of the nerve impulse. 3. Perfusing the electrode with Ba2+ (1‐3 mM) caused the appearance of a second negative‐going component of the nerve impulse. Local application of Cd2+ (0.1 mM) had little affect on this component of the nerve impulse. 4. Perfusing the electrode with 4‐aminopyridine (4‐AP) and/or tetraethylammonium (TEA) caused the appearance of a second negative‐going component o..