P-type calcium channels in rat central and peripheral neurons
I M Mintz1, M E Adams, B P Bean
1Department of Neurobiology, Harvard Medical School, Boston, Massachusetts 02115.
Abstract:
The peptide toxin omega-Aga-IVA blocked P-type Ca2+ channel current in rat Purkinje neurons (KD approximately 2 nM) but had no effect on identified T-type, L-type, or N-type currents in a variety of central and peripheral neurons. omega-Aga-IVA blocked a substantial fraction of high threshold Ca2+ channel current in neurons from the hippocampal CA1 region (mean 26%), visual cortex (32%), spinal cord (45%), and dorsal root ganglia (23%), but less in hippocampal CA3 neurons (14%) and none in sympathetic neurons. In all cases, omega-Aga-IVA block could be reversed by a brief train of strong depolarizations. There was no overlap between current blocked by omega-Aga-IVA and the fractions blocked by dihydropyridines and omega-conotoxin GVIA, but not all current resistant to dihydropyridines and omega-conotoxin was blocked by omega-Aga-IVA. The results suggest that omega-Aga-IVA is highly selective for P-type channels and that many central neurons and some peripheral neurons possess substantial P-type current.
Related Concept Videos
The Role of Ion Channels in Neuronal Computation
Sometimes a single EPSP is strong enough to induce an action potential in the postsynaptic neuron. However, multiple presynaptic inputs must often create EPSPs around the same time for the postsynaptic neuron to be sufficiently depolarized to fire an action potential.
Voltage-gated Ion Channels
Generally, all voltage-gated ion channels have a 'voltage-sensing domain' that spans the lipid bilayer. The charged residues in the sensor move in response to the membrane potential changes that open the channel allowing ions movement. There are several types of...
Mechanically-gated Ion Channels
Feedback Regulation of Calcium Concentration
Various transmembrane receptors, such as G protein-coupled receptors (GPCRs), elicit a response to extracellular signals by increasing cytosolic calcium. Activated GPCRs...
Ligand-Gated Ion Channel Receptor: Gating Mechanism


