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 prolo nged exposure to a low Ca2+ medium could induce these neurons to fire burst s of spikes. In this study, we performed a systematic exploration of the sp ontaneous activity of the guinea pig MVN neurons by extracellular recording s in slices perfused either with a low Ca2+-high Mg2+ medium, or with ACSF added with omega -agatoxin-IVA and with omega -conotoxin-GVIA, The percenta ge of recorded neurons which fired bursts, was 67% in low Ca2+-high Mg2+ me dium and 34% under the action of Ca2+ channel blockers. These results show that the sensitivity of the firing properties to diva lent cations is not s hared by all of the MVN neurons and that the regularity of firing of a clas s of MVN neurons depends on the Ca2+ channels they express in their membran es. (C) 2001 Elsevier Science Ireland Ltd. All rights reserved.