Calcium channel gating and modulation by transmitters depend on cellular compartmentalization.
Voltage-gated Ca2+ channels participate in dendritic integration, yet functional properties of Ca2+ channels and mechanisms of their modulation by neurotransmitters in dendrites are unknown. Here we report how pharmacologically 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 only that Ca2+ channel populations differentially contribute to somatic and dendritic currents but also that families of Ca2+ channels display gating properties and neurotransmitter modulation that depend on channel compartmentalization. By comparison with their somatic counterparts, dendritic N-type Ca2+ currents were hypersensitive to neurotransmitters and G proteins. Single-channel analysis showed that dendrites express a unique N-type channel that has enhanced interaction with Gbetagamma. Thus Ca2+ channels in dendrites seem to be specialized elements with unique regulatory mechanisms.
Delmas
P
P
Wellcome Laboratory for Molecular Pharmacology, Department of Pharmacology, University College London, Gower Street, London WC1E 6BT UK. ucklpds@ucl.ac.uk
Abogadie
F C
FC
Buckley
N J
NJ
Brown
D A
DA
D000818:Animals; D020864:Calcium Channels, N-Type / Q000502:physiology*; D002478:Cells, Cultured; D003712:Dendrites / Q000502:physiology; D019204:GTP-Binding Proteins / Q000502:physiology; D015640:Ion Channel Gating / Q000502:physiology; D007700:Kinetics; D008564:Membrane Potentials; D016501:Neurites / Q000502:physiology; D009474:Neurons / Q000502:physiology*; D018377:Neurotransmitter Agents / Q000502:physiology*; D018408:Patch-Clamp Techniques; D051381:Rats; D017783:Superior Cervical Ganglion / Q000502:physiology
D020864:Calcium Channels, N-Type; D018377:Neurotransmitter Agents; D019204:GTP-Binding Proteins