ArticleBritish journal of pharmacology1995
[3H]-lifarizine, a high affinity probe for inactivated sodium channels.
Article in British journal of pharmacology, 1995. The graph could read no effect estimate from its abstract, so it casts no vote on the map. Cited by 2 papers.
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Who cites it
2 citing papers in PubMed, 20 citations in OpenAlex.
- Chemical and Biological Tools for the Study of Voltage-Gated Sodium Channels in Electrogenesis and Nociception.Chembiochem : a European journal of chemical biology · 2022Review
- Inhibition by lifarizine of intracellular Ca2+ rises and glutamate exocytosis in depolarized rat cerebrocortical synaptosomes and cultured neurones.British journal of pharmacology · 1996Article
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Authors and funding
5 authors at 1 institution in 1 country.
Funding
No grant is acknowledged in the PubMed record.
Abstract
1. [3H]-lifarizine bound saturably and reversibly to an apparently homogeneous class of high affinity sites in rat cerebrocortical membranes (Kd = 10.7 +/- 2.9 nM; Bmax = 5.10 +/- 1.43 pmol mg-1 protein). 2. The binding of [3H]-lifarizine was unaffected by sodium channel toxins binding to site 1 (tetrodotoxin), site 3 (alpha-scorpion venom) or site 5 (brevetoxin), Furthermore, lifarizine at concentrations up to 10 microM had no effect on [3H]-saxitoxin (STX) binding to toxin site 1. Lifarizine displaced [3H]-batrachotoxinin-A 20-alpha-benzoate (BTX) binding with moderate affinity (pIC50 7.31 +/- 0.24) indicating an interaction with toxin site 2. However, lifarizine accelerated the dissociation of [3H]-BTX and decreased both the affinity and density of sites labelled by [3H]-BTX, suggesting an allosteric interaction with toxin site 2. 3. The binding of [3H]-lifarizine was voltage-sensitive, binding to membranes with higher affinity than to synaptosomes (pIC50 for cold lifarizine = 7.99 +/- 0.09 in membranes and 6.68 +/- 0.14 in synaptosomes). Depolarization of synaptosomes with 130 mM KCl increased the affinity of lifarizine almost 10 fold (pIC50 = 7.86 +/- 0.25). This suggests that lifarizine binds selectively to inactivated sodium channels which predominate both in the membrane preparation and in the depolarized synaptosomal preparation. 4. There was negligible [3H]-lifarizine and [3H]-BTX binding to solubilized sodium channels, although [3H]-STX binding was retained under these conditions. 5. The potencies of a series of compounds in displacing [3H]-lifarizine from rat cerebrocortical membranes correlated well with their affinities for inactivated sodium channels estimated from whole-cell voltage clamp studies in the mouse neuroblastoma cell line, NIE-115 (r=0.96).6. These results show that [3H]-lifarizine is a high affinity ligand for neuronal sodium channels which potently and selectively labels a site, allosterically linked to toxin binding site 2, associated within activated sodium channels.
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