INHIBITION OF TRANSMITTER RELEASE FROM SYMPATHETIC NERVE ENDINGS BY ω‐CONOTOXIN

Abstract

1. The effects of the calcium channel blocker, ω‐conotoxin, on sympathetic neuroeffector function in the guinea‐pig vas deferens have been investigated using a combination of mechanical and electrophysiological recording techniques. 2. Diphasic contractions evoked by electrical field stimulation were irreversibly abolished by ω‐conotoxin (10–100 nmol/L). 3. Electrically evoked excitatory junction potentials and currents were irreversibly blocked by ω‐conotoxin (10–100 nmol/L). Spontaneous excitatory junction potentials and currents were unaffected by this treatment. 4. ω‐Conotoxin did not block impulse propagation in the nerve terminals. However, in three of four experiments ω‐conotoxin caus..