Activity-dependent changes in intracellular calcium in myenteric neurons

Area of Science:

• Neuroscience
• Gastroenterology

Background:

• The myenteric plexus controls gastrointestinal motility.
• Understanding neuronal calcium dynamics is crucial for enteric nervous system function.

Purpose of the Study:

• To investigate the spatial distribution and changes in intracellular calcium concentration ([Ca2+]i) in myenteric neurons.
• To correlate calcium dynamics with electrical activity in different neuronal compartments.

Main Methods:

• Fura 2 imaging was used to measure [Ca2+]i in guinea pig duodenal myenteric neurons.
• Simultaneous intracellular voltage recordings were performed.
• Measurements were taken in both S-type and AH-type neurons.

Main Results:

• Action potentials in myenteric neuron cell bodies triggered rapid [Ca2+]i increases in both cell bodies and processes.
• No significant delay was observed between calcium changes in somata and processes, indicating electrical signal spread.
• Calcium removal was faster in neuronal processes compared to cell bodies.
• In AH neurons, the [Ca2+]i transient duration was shorter than the after-spike hyperpolarization.

Conclusions:

• Both S-type and AH-type myenteric neurons possess voltage-gated calcium channels in their somata and processes.
• Electrical signals, not diffusion, primarily drive rapid intracellular calcium changes in myenteric neurons.
• Differences in calcium removal rates may relate to neuronal morphology (surface-to-volume ratio).