Mild gastritis alters voltage-sensitive sodium currents in gastric sensory neurons in rats.
OBJECTIVE
Visceral hypersensitivity can be found in more than one third of patients with dyspeptic symptoms. We hypothesized that peripheral sensitization plays an important role in the development of hypersensitivity.


METHODS
We induced mild gastritis in Sprague-Dawley rats by adding 0.1% iodoacetamide to the drinking water. The stomach was injected with a retrograde label to identify gastric sensory neurons. Nodose and T9, T10 dorsal root ganglia were removed 7 days after initiation of iodoacetamide treatment. The cells were dissociated and cultured for 3-8 hours before recording whole cell currents using the patch-clamp technique.


RESULTS
Iodoacetamide induced a mild gastritis. Although there were no changes in voltage-sensitive inward and outward currents in nodose neurons, the inward currents increased significantly in T9, T10 spinal neurons. A more detailed analysis of sodium currents showed that this was caused by an increase in the tetrodotoxin-resistant sodium current.


CONCLUSIONS
Mild gastritis increases the tetrodotoxin-resistant current in gastric spinal sensory neurons. Considering the importance of sodium currents as determinants of neuron excitability, this change may contribute to peripheral sensitization and enhanced neuron excitability.
Bielefeldt
Klaus
K
Department of Internal Medicine, University of Iowa, Iowa City, Iowa 52242, USA. Bielefeldt@uiowa.edu
Ozaki
Noriyuki
N
Gebhart
Gerald F
GF
D000477:Alkylating Agents; D000779:Anesthetics, Local / Q000494:pharmacology; D000818:Animals; D002478:Cells, Cultured; D004594:Electrophysiology; D005727:Ganglia, Spinal / Q000166:cytology; D005756:Gastritis / Q000139:chemically induced / Q000378:metabolism*; D007460:Iodoacetamide; D008297:Male; D008564:Membrane Potentials / Q000187:drug effects / Q000502:physiology; D009475:Neurons, Afferent / Q000166:cytology / Q000502:physiology*; D051381:Rats; D017207:Rats, Sprague-Dawley; D012964:Sodium / Q000378:metabolism*; D015222:Sodium Channels / Q000378:metabolism; D013270:Stomach / Q000294:innervation*; D013779:Tetrodotoxin / Q000494:pharmacology
D000477:Alkylating Agents; D000779:Anesthetics, Local; D015222:Sodium Channels; D013779:Tetrodotoxin; D012964:Sodium; D007460:Iodoacetamide