Electrophysiological Recording from Colonic Afferent Nerves in an Ex Vivo Rat Colon

Begin with an electrophysiology setup containing an immobilized mouse colon segment in a balanced electrolyte solution.

The colon has an exposed major pelvic ganglion with a pre-dissected colon afferent sensory nerve branch that transmits signals from the colon to the brain.

The colon is cannulated at both ends with three-way valves for saline infusion.

Fill the recording electrode and position it near the afferent nerve.

Apply mild suction to pull the nerve into the electrode, forming a tight seal.

Monitor the baseline nerve electrical signal and the colon's internal pressure.

Close the tap on the outlet cannula while continuously infusing the saline into the colon.

This causes a gradual rise in pressure inside the colon, resulting in colon distension and stimulating the afferent nerve.

Re-record the nerve signal and the colon pressure.

A gradual rise in the nerve signal with increased pressure confirms the afferent nerve stimulation.

Inspect a prepulled glass pipette under the dissecting microscope. Break the tip of the electrode with a pair of forceps, so that it is of a size compatible with the diameter of the nerve to be recorded. Following that, bevel the tip by placing it cl