Voltage-gated calcium channels contribute to the pattern of the resting discharge in guinea pig medial vestibular nucleus neurons.
In brainstem slices of guinea pigs perfused with artificial cerebro-spinal fluid (ACSF), the discharge of all the spontaneously active neurons of the medial vestibular nucleus (MVN) is regular. It has been reported that prolonged exposure to a low Ca(2+) medium could induce these neurons to fire bursts of spikes. In this study, we performed a systematic exploration of the spontaneous activity of the guinea pig MVN neurons by extracellular recordings in slices perfused either with a low Ca(2+)-high Mg(2+) medium, or with ACSF added with omega-agatoxin-IVA and with omega-conotoxin-GVIA. The percentage of recorded neurons which fired bursts, was 67% in low Ca(2+)-high Mg(2+) medium and 34% under the action of Ca(2+) channel blockers. These results show that the sensitivity of the firing properties to divalent cations is not shared by all of the MVN neurons and that the regularity of firing of a class of MVN neurons depends on the Ca(2+) channels they express in their membranes.
Ris
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University of Mons-Hainaut, Laboratory of Neurosciences, Place du Parc 20, B-7000, Mons, Belgium.
Godaux
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E
D000200:Action Potentials / Q000187:drug effects / Q000502:physiology; D000818:Animals; D002118:Calcium / Q000493:pharmacokinetics; D002121:Calcium Channel Blockers / Q000494:pharmacology; D015220:Calcium Channels / Q000502:physiology*; D006168:Guinea Pigs; D008274:Magnesium / Q000494:pharmacology; D009474:Neurons / Q000166:cytology / Q000502:physiology; D009924:Organ Culture Techniques; D014726:Vestibular Nuclei / Q000737:chemistry* / Q000166:cytology / Q000502:physiology*; D020867:omega-Agatoxin IVA / Q000494:pharmacology; D020866:omega-Conotoxin GVIA / Q000494:pharmacology
D002121:Calcium Channel Blockers; D015220:Calcium Channels; D020867:omega-Agatoxin IVA; D020866:omega-Conotoxin GVIA; D008274:Magnesium; D002118:Calcium