T-Type Ca2+Current Properties Are Not Modified by Ca2+Channel β Subunit Depletion in Nodosus Ganglion Neurons

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Abstract
At the molecular level, our knowledge of the low voltage-activated Ca2+channel (T-type) has made little progress. Using an antisense strategy, we investigated the possibility that the T-type channels have a structure similar to high voltage-activated Ca2+channels. It is assumed that high voltage-activated channels are made of at least three components: a pore forming α1subunit combined with a cytoplasmic modulatory β subunit and a primarily extracellular α2δ subunit. We have examined the effect of transfecting cranial primary sensory neurons with generic anti-β antisense oligonucleotides. We show that in this cell type, blocking expression of all known β gene products does not affect T-type current, although it greatly decreases the current amplitude of high voltage-activated channels and modifies their voltage dependence. This suggests that β subunits are likely not constitutive of T-type Ca2+channels in this cell type.