T-TYPE CA2-SUBUNIT DEPLETION IN NODOSUS GANGLION NEURONS( CURRENT PROPERTIES ARE NOT MODIFIED BY CA2+ CHANNEL BETA)

At the molecular level, our knowledge of the low voltage-activated Ca2 + channel (T-type) has made little progress. Using an antisense strate gy, we investigated the possibility that the T-type channels have a st ructure similar to high voltage-activated Ca2+ channels. It is assumed that high voltage-activated channels are made of at least three compo nents: a pore forming alpha(1) subunit combined with a cytoplasmic mod ulatory beta subunit and a primarily extracellular alpha(2) delta subu nit. We have examined the effect of transfecting cranial primary senso ry neurons with generic anti-beta antisense oligonucleotides. We show that in this cell type, blocking expression of all known beta gene pro ducts does not affect T-type current, although it greatly decreases th e current amplitude of high voltage-activated channels and modifies th eir voltage dependence. This suggests that beta subunits are likely no t constitutive of T-type Ca2+ channels in this cell type.