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Phorbol ester and lignocaine or pentobarbitone interactions at presynaptic axons
1School of Biomedical Science, Queen's University, Belfast, UK.
Neuroreport
|February 1, 1992
Summary
Protein kinase C activation enhances the potency of local anesthetics like lignocaine and tetrodotoxin. This suggests protein kinase C phosphorylation of channel proteins increases anesthetic effectiveness in nerve cells.
Area of Science:
- Neuroscience
- Pharmacology
- Molecular Biology
Background:
- Unmyelinated axons and en passant synapses are crucial for neuronal signaling.
- Protein kinase C (PKC) plays a role in cellular signaling pathways.
- The interaction between anesthetics and PKC activation in neuronal function requires further elucidation.
Purpose of the Study:
- To investigate the modulatory effect of protein kinase C activation on the interaction between anesthetics and neuronal ion channels.
- To determine if PKC activation alters the potency of common anesthetics on sodium currents.
Main Methods:
- Studied electrical responses in unmyelinated axons using field current analysis.
- Resolved electrical responses into sodium (Na), potassium (K), and calcium (Ca) components.
- Utilized electrode polarization and potassium-conductance blockers for precise measurements.
- Administered phorbol dibutyrate to activate protein kinase C.
Main Results:
- Phorbol dibutyrate significantly increased the potency of lignocaine, pentobarbitone, and tetrodotoxin.
- Potency increases for Na current ranged from 2.35 to 2.67 fold.
- The observed potentiation was independent of changes in membrane potential.
Conclusions:
- Protein kinase C activation enhances the effectiveness of certain anesthetics on neuronal sodium channels.
- PKC-mediated phosphorylation of membrane channel proteins is a likely mechanism for this potentiation.
- Findings suggest a novel interaction pathway influencing anesthetic action in the nervous system.