Characterizing the expression of voltage gated calcium channels in rat superior cervical ganglia

Abstract

Voltage gated calcium channels (Cav) are comprised of several different subunits necessary to achieve proper function. Some of the subunits (β, α2‐γ) contribute to not only channel properties, but to trafficking. In heterologous expression systems that lack endogenous Cav channels, pore‐forming subunits must be co‐expressed with accessory subunits for channel localization to the plasma membrane and for proper function. In some neurons expression of an exogenous pore, without co‐expression of its respective subunits, can result in a functional channel. We investigate the channel expression in the cell body of rat superior cervical ganglion neurons (SCG) using whole cell patch clamping. SCG neurons express mainly type 2 Cav channels. Interestingly, when the cDNA encoding Cav pore‐forming subunits are injected intranuclearly into SCG neurons, large increases in current density corresponding to recombinant Cav channel expression are observed in a subunit specific manner. These data suggest that pre‐formed, sub‐unit specific “slots” exist in SCG neurons to allow for the expression, trafficking and function of certain Cav channel subunits, but not others. Using this approach, we observe significant increases in calcium current density following the expression of Cav 2.1, mCav2.3, Cav 1.3 subunits, but no increase in current density when Cav 2.2 or Cav 1.2 are injected. RO1 GM101023