Differential facilitation of N- and P/Q-type calcium channels during trains of action potential-like waveforms

J Physiol. 2002 Mar 1;539(Pt 2):419-31. doi: 10.1113/jphysiol.2001.013206.


Inhibition of presynaptic voltage-gated calcium channels by direct G-protein betagamma subunit binding is a widespread mechanism that regulates neurotransmitter release. Voltage-dependent relief of this inhibition (facilitation), most likely to be due to dissociation of the G-protein from the channel, may occur during bursts of action potentials. In this paper we compare the facilitation of N- and P/Q-type Ca(2+) channels during short trains of action potential-like waveforms (APWs) using both native channels in adrenal chromaffin cells and heterologously expressed channels in tsA201 cells. While both N- and P/Q-type Ca(2+) channels exhibit facilitation that is dependent on the frequency of the APW train, there are important quantitative differences. Approximately 20 % of the voltage-dependent inhibition of N-type I(Ca) was reversed during a train while greater than 40 % of the inhibition of P/Q-type I(Ca) was relieved. Changing the duration or amplitude of the APW dramatically affected the facilitation of N-type channels but had little effect on the facilitation of P/Q-type channels. Since the ratio of N-type to P/Q-type Ca(2+) channels varies widely between synapses, differential facilitation may contribute to the fine tuning of synaptic transmission, thereby increasing the computational repertoire of neurons.

Publication types

  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Action Potentials / physiology
  • Adrenal Glands / metabolism
  • Animals
  • Calcium Channels, N-Type / physiology*
  • Calcium Channels, P-Type / physiology*
  • Calcium Channels, Q-Type / physiology*
  • Cattle
  • Cells, Cultured
  • Electric Stimulation
  • Electrophysiology
  • Ion Channel Gating / physiology
  • Neuronal Plasticity / physiology
  • Neurons / metabolism
  • Neurotransmitter Agents / metabolism
  • Patch-Clamp Techniques
  • Recombinant Proteins / metabolism


  • Calcium Channels, N-Type
  • Calcium Channels, P-Type
  • Calcium Channels, Q-Type
  • Neurotransmitter Agents
  • Recombinant Proteins