Separation of M-like current and ERG current in NG108-15 cells

Area of Science:

• Neuroscience
• Molecular Biology
• Electrophysiology

Background:

• NG108-15 cells exhibit complex deactivation currents upon hyperpolarization.
• Understanding the specific ion channels responsible for these currents is crucial for neuronal function.

Purpose of the Study:

• To differentiate and characterize the fast and slow components of deactivation currents in NG108-15 cells.
• To identify the molecular correlates of these currents using pharmacological and molecular biology approaches.

Main Methods:

• Whole-cell voltage-clamp electrophysiology on differentiated NG108-15 cells.
• Application of selective ion channel blockers: Linopirdine (M-current) and E-4031/WAY-123.398 (ERG channel).
• Analysis of RNA transcripts for K+ channel family members (EAG, ERG, KCNQ).

Main Results:

• Deactivation currents resolved into fast and slow components.
• Linopirdine selectively inhibited the fast component (IC50 = 14.7 microM).
• E-4031 and WAY-123.398 predominantly inhibited the slow component (IC50 = 38 nM for E-4031).
• ERG currents showed low sensitivity to Linopirdine.
• RNA analysis detected ERG1, ERG2, EAGI, ELK1, ELK2, KCNQ2, and KCNQ3 transcripts.

Conclusions:

• The fast deactivation current component is identified as an M-like current.
• The slow deactivation current component is identified as a deactivating ERG current.
• KCNQ2/KCNQ3 likely form the M-like current, and ERG1/ERG2 likely form the deactivating ERG current.