Intracellular recordings from sympathetic preganglionic neurones

Area of Science:

• Neuroscience
• Autonomic Nervous System Physiology
• Spinal Cord Research

Background:

• Sympathetic preganglionic neurones (SPN) are crucial for regulating involuntary bodily functions.
• Understanding SPN electrophysiology is key to deciphering autonomic control.
• Previous research has not fully detailed the somatic and dendritic responses of SPN to specific inputs.

Purpose of the Study:

• To investigate the electrophysiological properties of the soma dendritic region of SPN in anaesthetised cats.
• To characterize the neuronal response to excitation of the third thoracic white ramus and orthodromic inputs.

Main Methods:

• Intracellular recordings were performed on SPN in the T3 spinal segment of anaesthetised cats.
• Neuronal activity was stimulated via the third thoracic white ramus and orthodromic pathways.
• Membrane potential changes and action potential characteristics were analysed.

Main Results:

• Most recorded SPN exhibited short-duration action potentials.
• A significant proportion of the studied neurones were actively firing.
• Depolarizing and hyperpolarizing membrane potential shifts were observed.
• These membrane potential changes were transient, with decreases lasting less than 40 msec.
• A modest depolarization of 5 mV was sufficient to trigger neuronal discharge.

Conclusions:

• SPN possess rapid electrophysiological properties, including short action potentials and swift membrane potential fluctuations.
• The observed responses indicate a high degree of neuronal excitability in SPN.
• These findings contribute to a deeper understanding of the functional dynamics of the sympathetic nervous system at the spinal level.