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PLC‐dependent intracellular Ca 2+ release was associated with C 6 ‐ceramide‐induced inhibition of Na + current in rat granule cells
Author(s) -
Liu Zheng,
Fei XiaoWei,
Fang YanJia,
Shi WenJie,
Zhang YuQiu,
Mei YanAi
Publication year - 2008
Publication title -
journal of neurochemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.75
H-Index - 229
eISSN - 1471-4159
pISSN - 0022-3042
DOI - 10.1111/j.1471-4159.2008.05562.x
Subject(s) - ceramide , intracellular , chemistry , ryanodine receptor , inositol , biophysics , calmodulin , phospholipase c , endoplasmic reticulum , egta , biochemistry , receptor , biology , calcium , apoptosis , enzyme , organic chemistry
In this report, the effects of C 6 ‐ceramide on the voltage‐gated inward Na + currents ( I Na ), two types of main K + current [outward rectifier delayed K + current ( I K ) and outward transient K + current ( I A )], and cell death in cultured rat cerebellar granule cells were investigated. At concentrations of 0.01–100 μM, ceramide produced a dose‐dependent and reversible inhibition of I Na without alteration of the steady‐state activation and inactivation properties. Treatment with C 2 ‐ceramide caused a similar inhibitory effect on I Na . However, dihydro‐C 6 ‐ceramide failed to modulate I Na . The effect of C 6 ‐ceramide on I Na was abolished by intracellular infusion of the Ca 2+ ‐chelating agent, 1,2‐bis (2‐aminophenoxy) ethane‐ N , N , N 9, N 9‐tetraacetic acid, but was mimicked by application of caffeine. Blocking the release of Ca 2+ from the sarcoplasmic reticulum with ryanodine receptor blocker induced a gradual increase in I Na amplitude and eliminated the effect of ceramide on I Na . In contrast, the blocker of the inositol 1,4,5‐trisphosphate‐sensitive Ca 2+ receptor did not affect the action of C 6 ‐ceramide. Intracellular application of GTPγS also induced a gradual decrease in I Na amplitude, while GDPβS eliminated the effect of C 6 ‐ceramide on I Na . Furthermore, the C 6 ‐ceramide effect on I Na was abolished after application of the phospholipase C (PLC) blockers and was greatly reduced by the calmodulin inhibitors. Fluorescence staining showed that C 6 ‐ceramide decreased cell viability and blocking I Na by tetrodotoxin did not mimic the effect of C 6 ‐ceramide, and inhibiting intracellular Ca 2+ release by dantrolene could not decrease the C 6 ‐ceramide‐induced cell death. We therefore suggest that increased PLC‐dependent Ca 2+ release through the ryanodine‐sensitive Ca 2+ receptor may be responsible for the C 6 ‐ceramide‐induced inhibition of I Na , which does not seem to be associated with C 6 ‐ceramide‐induced granule neuron death.