Slow outward tail currents in molluscan bursting pacemaker neurons: two components differing in temperature...

Area of Science:

• Neuroscience
• Cellular Electrophysiology

Background:

• Bursting pacemaker neurons in Tritonia and Aplysia regulate neural timing.
• The slow outward tail current is critical for burst termination and inter-burst hyperpolarization.

Purpose of the Study:

• To elucidate the ionic requirements of the slow outward tail current in bursting pacemaker neurons.
• To understand the contribution of different ionic currents to pacemaker activity timing.

Main Methods:

• Voltage-clamp experiments on neuron somata.
• Rapid extracellular perfusion with varying ionic solutions.
• Current-voltage relationship and reversal potential measurements.

Main Results:

• The slow outward tail current is composed of at least two distinct currents.
• Temperature significantly influences the ionic composition of the tail current.
• Both potassium and a potassium-insensitive outward current, dependent on calcium influx, were identified.

Conclusions:

• The slow outward tail current involves multiple ionic components, varying with temperature.
• Calcium influx is essential for activating both identified outward currents.
• These findings reconcile previous studies and propose a mechanism for temperature compensation in pacemaker cells.