Multisite optical recording of excitability in the enteric nervous system.
A multisite optical recording technique consisting of an array of 464 photodiodes was used to measure dynamic changes in transmembrane potentials (Vm) of guinea-pig and mouse enteric neurones stained with the voltage-sensitive dye Di-8-ANEPPS. Optical recordings of Vm changes in enteric neurones which were evoked by depolarizing current pulses or synaptic activation mirrored the Vm changes measured intracellularly in the same neurone. Action potentials had fractional change in fluorescence of -0.09 +/- 0.06% and their peak to peak noise level was 20 +/- 14% of the action potential amplitude. Optical recordings after electrical stimulation of interganglionic nerve strands revealed slow EPSPs, nicotinergic supra- and subthreshold fast EPSPs as well as propagation of action potentials along interganglionic strands. Local application of acetylcholine onto a single ganglion induced reproducibly and dose dependently action potential discharge demonstrating the feasibility of neuropharmacological studies. The optical mapping made it possible to record action potentials simultaneously in a large number of neurones with high spatiotemporal resolution that is unattainable by conventional techniques. This technique presents a powerful tool to study excitability spread within enteric circuits and to assess differential activation of enteric populations in response to a number of stimuli which modulate neuronal activity directly or through synaptic mechanisms.
Neunlist
M
M
Department of Physiology, School of Veterinary Medicine, Bischofsholer Damm 15/102, D-30173 Hannover, Germany. mneunlis@win.tiho-hannover.de
Peters
S
S
Schemann
M
M
D000109:Acetylcholine / Q000494:pharmacology; D000200:Action Potentials / Q000187:drug effects / Q000502:physiology; D000818:Animals; D004396:Coloring Agents; D004594:Electrophysiology / Q000379:methods*; D019706:Excitatory Postsynaptic Potentials / Q000187:drug effects / Q000502:physiology*; D006168:Guinea Pigs; D051379:Mice; D008807:Mice, Inbred BALB C; D055095:Optics and Photonics; D013268:Stimulation, Chemical; D013368:Submucous Plexus / Q000502:physiology*; D014665:Vasodilator Agents / Q000494:pharmacology
D004396:Coloring Agents; D014665:Vasodilator Agents; D000109:Acetylcholine