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Calcium and calcium‐activated currents in vagotomized rat primary vagal afferent neurons
Author(s) -
Lancaster Eric,
Oh Eun Joo,
Gover Tony,
Weinreich Daniel
Publication year - 2002
Publication title -
the journal of physiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.802
H-Index - 240
eISSN - 1469-7793
pISSN - 0022-3751
DOI - 10.1113/jphysiol.2001.013121
Subject(s) - chemistry , vagotomy , calcium , depolarization , endocrinology , medicine , organic chemistry
Adult inferior vagal ganglion neurons (nodose ganglion neurons, NGNs) were acutely isolated 4–6 days after section of their peripheral axons (vagotomy) and examined with the whole‐cell patch‐clamp technique. A subset (∼25 %) of vagotomized NGNs displayed depolarizing after‐potentials (DAPs), not present in control NGNs. DAPs were inhibited by niflumic acid (125 μ m ) or cadmium (100 μ m ), and had a reversal potential near E Cl , indicating that they were due to Ca 2+ ‐activated chloride current ( I Cl(Ca) ). N‐type, L‐type, T‐/R‐ and other types of voltage‐dependent Ca 2+ channels provided about 43, 2, 16 and 40 % of the trigger Ca 2+ for DAP generation, respectively. Intracellular Ca 2+ concentration ([Ca 2+ ] i ) was estimated using fura‐2 fluorescence. Resting [Ca 2+ ] i and peak [Ca 2+ ] i elevation induced by activating Ca 2+ ‐induced Ca 2+ release (CICR) stores with 10 m m caffeine were not significantly different among control NGNs, vagotomized NGNs with DAPs and vagotomized NGNs without DAPs, averaging 54 ± 7.9 ( n = 19 ; P = 0.49 ) and 2022 ± 1059 n m ( n = 19 ; P = 0.44 ), respectively. Blocking CICR with 10 μ m ryanodine reduced DAP amplitude by ∼37 %. Ca 2+ influx induced by action potential waveforms was increased by over 250 % in vagotomized NGNs with DAPs (19.0 ± 2.1 pC) compared to control NGNs (5.0 ± 0.8 pC) or vagotomized NGNs without DAPs (7.0 ± 0.8 pC). L‐type, N‐type, T‐/R‐type and other types of Ca 2+ influx were increased proportionately in vagotomized NGNs with DAPs. In conclusion, a subset of vagotomized NGNs have increased Ca 2+ currents and express I Cl(Ca) . These NGNs respond electrically to increases in [Ca 2+ ] i during regeneration.