A zinc-dependent Cl- current in neuronal somata.

Area of Science:

• Neuroscience
• Cellular Electrophysiology
• Trace Element Signaling

Background:

• Extracellular Zn2+ is known to modulate ion channel activity.
• The electrophysiological effects of intracellular Zn2+ at physiological concentrations are not well understood.
• Investigating the role of cytoplasmic Zn2+ in neuronal function is crucial for understanding cellular excitability.

Purpose of the Study:

• To investigate the effects of lower levels of cytoplasmic Zn2+ on neuronal somata.
• To determine if cytoplasmic zinc influences ion channel conductances.
• To elucidate the mechanisms by which cytoplasmic zinc modulates neuronal electrical properties.

Main Methods:

• Whole-cell patch-clamp recordings were performed on fish retinal ganglion cell somata.
• Zn2+-selective chelators, Zn2+-preferring ionophores, and exogenous Zn2+ were utilized.
• Electrophysiological parameters were measured to assess the impact of zinc modulation.

Main Results:

• Cytoplasmic zinc was found to facilitate the downward regulation of a background Cl- conductance by endogenous protein kinase C (PKC).
• This regulation was sustained by nanomolar levels of free Zn2+.
• This represents a novel mechanism where zinc-dependent PKC controls neuronal conductance.

Conclusions:

• Cytoplasmic zinc plays a significant role in regulating neuronal excitability through modulation of background Cl- conductances.
• The findings provide the first electrophysiological evidence for zinc-dependent PKC activity in neurons.
• Background Cl- conductances are susceptible to modulation by intracellular zinc levels, impacting neuronal electrical properties.