Nitric oxide signalling augments neuronal voltage-gated L-type (Ca(v)1) and P/q-type (Ca(v)2.1) channels in the mouse medial nucleus of the trapezoid body

PLoS One. 2012;7(2):e32256. doi: 10.1371/journal.pone.0032256. Epub 2012 Feb 28.

Abstract

Nitric Oxide (NO) is a diffusible second messenger that modulates ion channels, intrinsic excitability and mediates synaptic plasticity. In light of its activity-dependent generation in the principal neurons of the medial nucleus of the trapezoid body (MNTB), we have investigated its potential modulatory effects on native voltage-gated calcium channels (Ca(V)) within this nucleus. Whole-cell patch recordings were made from brain slices from P13-15 CBA mice. Slices were incubated with the inhibitor of neuronal nitric oxide synthase (nNOS) 7-nitroindazole (10 µM) and pharmacological blockers used to isolate Ca(2+) current subtypes. Unpaired observations in the presence and absence of the NO-donors sodium nitroprusside (SNP, 100 µM) or Diethyl-ammonium-nonoate (DEA, 100 µM) were made to elucidate NO-dependent modulation of the expressed Ca(V) subtypes. A differential effect of NO on the calcium channel subtypes was observed: Ca(V)1 and Ca(V)2.1 (L+R- and P/Q+R-type) conductances were potentiated, whereas N+R-type (Ca(V)2.2) and R-type (Ca(V)2.3) current amplitudes were unaffected. L+R-type currents increased from 0.36 ± 0.04 nA to 0.64 ± 0.11 nA and P/Q+R-type from 0.55 ± 0.09 nA to 0.94 ± 0.05 nA, thereby changing the balance and relative contribution of each subtype to the whole cell calcium current. In addition, N+R-type half-activation voltage was left shifted following NO exposure. NO-dependent modulation of P/Q+R and N+R-type, but not L+R-type, channels was removed by inhibition of soluble guanylyl cyclase (sGC) activity. This data demonstrates a differential effect of NO signalling on voltage-gated calcium entry, by distinct NO-dependent pathways.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Calcium / metabolism
  • Calcium Channels / metabolism*
  • Guanylate Cyclase / metabolism
  • Indazoles / pharmacology
  • Mice
  • Nitric Oxide / metabolism*
  • Nitric Oxide Donors / pharmacology
  • Nitroprusside / pharmacology
  • Receptors, Cytoplasmic and Nuclear / metabolism
  • Signal Transduction / drug effects
  • Soluble Guanylyl Cyclase

Substances

  • Calcium Channels
  • Indazoles
  • Nitric Oxide Donors
  • Receptors, Cytoplasmic and Nuclear
  • Nitroprusside
  • Nitric Oxide
  • Guanylate Cyclase
  • Soluble Guanylyl Cyclase
  • Calcium
  • 7-nitroindazole