Phorbol ester and lignocaine or pentobarbitone interactions at presynaptic axons.
The interaction between anaesthetics and protein kinase C activation was studied in unclamped field currents from unmyelinated axons which give rise to en passant synapses. Electrical responses could be resolved into Na, K and Ca components revealed by electrode polarisation pretreatment with blockers of K-conductances. In the presence of phorbol dibutyrate, there was an increase in the potency of lignocaine, pentobarbitone and tetrodotoxin: for the Na current, the potency increased by 2.67 +/- 0.64, 2.35 and 2.47 fold respectively. The potentiation does not appear to be any indirect result of changed membrane potential. It is suggested that protein kinase C phosphorylation of membrane channel proteins increases the effectiveness of these substances.
McGivern
J
J
School of Biomedical Science, Queen's University, Belfast, UK.
Scholfield
C N
CN
D000818:Animals; D001369:Axons / Q000187:drug effects*; D004347:Drug Interactions; D004566:Electrodes; D066298:In Vitro Techniques; D008012:Lidocaine / Q000494:pharmacology*; D010424:Pentobarbital / Q000494:pharmacology*; D015240:Phorbol 12,13-Dibutyrate / Q000494:pharmacology*; D051381:Rats; D013574:Synaptosomes / Q000187:drug effects*; D013779:Tetrodotoxin / Q000494:pharmacology*
D015240:Phorbol 12,13-Dibutyrate; D013779:Tetrodotoxin; D008012:Lidocaine; D010424:Pentobarbital