Calcium channel gating and modulation by transmitters depend on cellular compartmentalization

Voltage-gated Ca2+ channels participate in dendritic integration, yet funct ional properties of Ca2+ channels and mechanisms of their modulation by neu rotransmitters in dendrites are unknown. Here we report how pharmacological ly identified Ca2+ channels behave in different neural compartments. Whole- cell and cell-attached patch-clamp recordings were made on both cell bodies and electrically isolated dendrites of sympathetic neurons. We found not o nly that Ca2+ channel populations differentially contribute to somatic and dendritic currents but also that families of Ca2+ channels display gating p roperties and neurotransmitter modulation that depend on channel compartmen talization. By comparison with their somatic counterparts,; dendritic N-typ e Ca2+ currents were hypersensitive to neurotransmitters and C proteins. Si ngle-channel analysis showed that dendrites express a unique N-type channel that has enhanced interaction with G beta gamma. Thus Ca2+ channels in den drites seem to be specialized elements with unique regulatory mechanisms.