The actions of phorbol esters upon isolated calcium currents of Helix aspersa neurones

1. Voltage-clamp recordings have been made from identified neurones in the suboesophageal ganglia of Helix aspersa. 2. Calcium currents were isolated pharmacologically and studied under two-electrode voltage-clamp. 3. PdBu but not PMA caused a transient enhancement followed by an irreversible inhibition of the calcium current. 4. It is concluded that activation of protein kinase C within these neurones may show selectivity with respect to the exogenous activator used.