High affinity block by nimodipine of the internal calcium elevation in chronically depolarized rat cerebellar granule neurons.

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Marchetti C, Usai C

High affinity block by nimodipine of the internal calcium elevation in chronically depolarized rat cerebellar granule neurons.

Neurosci Lett. 1996 Mar 29;207(2):77-80.

PubMed ID

8731425 [ View in PubMed

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Abstract

Chronic depolarization enhances survival of cultured rat cerebellar granule neurons by elevating the internal calcium concentration ([Ca2+]i). In Fura2-loaded cells maintained in 25 mM KCl, [Ca2+]i was close to 150 nM and decreased to approximately 50 nM when KCl was lowered to 5.4 mM. The effect of nimodipine (IC50 = 0.45 nM) was similar to depolarization removal, while agatoxin IVA (up to 500 nM) was ineffective. In whole-cell-clamp experiments, the IC50 for current inhibition was 57 nM, while with transient, KCl-induced depolarizations, the dose dependence of nimodipine inhibition had a 'double-affinity' shape, with IC50(1) = 0.30 nM and IC50(2) = 71 nM. We concluded that L-type calcium channels are the main responsible of the elevated internal calcium level necessary for survival in these neurons. These channels do not inactivate and bind nimodipine with different affinity, depending on their state.

DrugBank Data that Cites this Article

Drug Targets

Drug	Target	Kind	Organism	Pharmacological Action	Actions
Nimodipine	Voltage-dependent L-type calcium channel subunit alpha-1C	Protein	Humans	Yes	Inhibitor	Details