Differential contribution of L-, N-, and P/Q-type calcium channels to [Ca2+]i changes evoked by kainate in hippocampal neurons

Neurochem Res. 2008 Aug;33(8):1501-8. doi: 10.1007/s11064-008-9618-8. Epub 2008 Mar 27.

Abstract

We investigated the contribution of L-, N- and P/Q-type Ca(2+) channels to the [Ca(2+)](i) changes, evoked by kainate, in the cell bodies of hippocampal neurons, using a pharmacological approach and Ca(2+) imaging. Selective Ca(2+) channel blockers, namely nitrendipine, omega-Conotoxin GVIA (omega-GVIA) and omega-Agatoxin IVA (omega-AgaIVA) were used. The [Ca(2+)](i) changes evoked by kainate presented a high variability, and were abolished by NBQX, a AMPA/kainate receptor antagonist, but the N-methyl-D-aspartate (NMDA) receptor antagonist, D-AP5, was without effect. Each Ca(2+) channel blocker caused differential inhibitory effects on [Ca(2+)](i) responses evoked by kainate. We grouped the neurons for each blocker in three subpopulations: (1) neurons with responses below 60% of the control; (2) neurons with responses between 60% and 90% of the control, and (3) neurons with responses above 90% of the control. The inhibition caused by nitrendipine was higher than the inhibition caused by omega-GVIA or omega-AgaIVA. Thus, in the presence of nitrendipine, the percentage of cells with responses below 60% of the control was 41%, whereas in the case of omega-GVIA or omega-AgaIVA the values were 9 or 17%, respectively. The results indicate that hippocampal neurons differ in what concerns their L-, N- and P/Q-type Ca(2+) channels activated by stimulation of the AMPA/kainate receptors.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Calcium / metabolism
  • Calcium Channel Blockers / metabolism
  • Calcium Channels, L-Type / metabolism*
  • Calcium Channels, N-Type / metabolism*
  • Calcium Channels, P-Type / metabolism*
  • Calcium Channels, Q-Type / metabolism*
  • Cells, Cultured
  • Excitatory Amino Acid Agonists / pharmacology*
  • Excitatory Amino Acid Antagonists / metabolism
  • Hippocampus* / cytology
  • Hippocampus* / drug effects
  • Hippocampus* / metabolism
  • Kainic Acid / pharmacology*
  • Neurons / cytology
  • Neurons / drug effects*
  • Neurons / metabolism
  • Nitrendipine / metabolism
  • Quinoxalines / metabolism
  • Rats
  • Rats, Wistar
  • omega-Agatoxin IVA / metabolism
  • omega-Conotoxin GVIA / metabolism

Substances

  • Calcium Channel Blockers
  • Calcium Channels, L-Type
  • Calcium Channels, N-Type
  • Calcium Channels, P-Type
  • Calcium Channels, Q-Type
  • Excitatory Amino Acid Agonists
  • Excitatory Amino Acid Antagonists
  • Quinoxalines
  • omega-Agatoxin IVA
  • 2,3-dioxo-6-nitro-7-sulfamoylbenzo(f)quinoxaline
  • omega-Conotoxin GVIA
  • Nitrendipine
  • Kainic Acid
  • Calcium