Fast calcium and voltage‐sensitive dye imaging in enteric neurones reveal calcium peaks associated with single action potential discharge

• Published in: The Journal of physiology Vol. 589; no. 24; pp. 5941 - 5947
• Main Authors: Michel, K., Michaelis, M., Mazzuoli, G., Mueller, K., Vanden Berghe, P., Schemann, M.
• Format: Journal Article
• Language: English
• Published: Oxford, UK Blackwell Publishing Ltd 15.12.2011; Wiley Subscription Services, Inc; Blackwell Science Inc
• Subjects: Action Potentials - physiology; Aniline Compounds - pharmacology; Animals; Calcium; Calcium - physiology; Calcium Channel Blockers - pharmacology; Excitatory Postsynaptic Potentials - physiology; Fluorescent Dyes - pharmacology; Guinea Pigs; Humans; Ileum - physiology; Male; Myenteric Plexus - physiology; Neurons - physiology; Nicotine - pharmacology; Nicotinic Agonists - pharmacology; omega-Conotoxins - pharmacology; Pyridinium Compounds - pharmacology; Ruthenium Red - pharmacology; Techniques for Physiology; Tetrodotoxin - pharmacology; Voltage-Sensitive Dye Imaging; Xanthenes - pharmacology
• ISSN: 0022-3751; 1469-7793
• DOI: 10.1113/jphysiol.2011.219550

Non‐technical summary  Imaging of slow, long‐lasting changes in intracellular Ca2+ levels ([Ca2+]i) is a common method to assess neuronal activity. We found that fast [Ca2+]i imaging (≥200 Hz sampling rate) may be a new option to record fast neuronal events including spike discharge and fast synaptic transmission in enteric neurones. These [Ca2+]i peaks required opening of voltage‐gated sodium and calcium channels as well as Ca2+ release from intracellular stores.   Slow changes in [Ca2+]i reflect increased neuronal activity. Our study demonstrates that single‐trial fast [Ca2+]i imaging (≥200 Hz sampling rate) revealed peaks each of which are associated with single spike discharge recorded by consecutive voltage‐sensitive dye (VSD) imaging in enteric neurones and nerve fibres. Fast [Ca2+]i imaging also revealed subthreshold fast excitatory postsynaptic potentials. Nicotine‐evoked [Ca2+]i peaks were reduced by ω‐conotoxin and blocked by ruthenium red or tetrodotoxin. Fast [Ca2+]i imaging can be used to directly record single action potentials in enteric neurones. [Ca2+]i peaks required opening of voltage‐gated sodium and calcium channels as well as Ca2+ release from intracellular stores.