Nicardipine inhibits N-type calcium channels in dbcAMP-diferentiated neuroblastoma×glioma hybrid cels(NG 108-15 ceLls)

Nicardipine inhibits N type calcium channels in dbcAMP differentiated neuroblastoma×glioma hybrid cells (NG 108 15 cells)

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AIM: To investigate the possibility of dihydropyridine inhibition of N type calcium channels. METHODS: Effects of nifedipine and nicardipine on the high K + induced intracellular Ca 2+ concentration ([Ca 2+ ] i) increase were studied by measuring [Ca 2+ ] i using the fluorescent indi￣cat￣or Fura 2. RESULTS: Pretreatment of cells with nifedipine 50 μmol·L -1 inhibited the high K + induc￣ed [Ca 2+ ] i transient by about 60 % ( n =3); however, pretreatment of cells with nicardipine 10 μmol·L -1 completely prevented the high K + evoked [Ca 2+ ] i increase in dibutyryl cyclic AMP (dbcAMP) differentiated NG 108 15 cells ( n =5). The high K + induced [Ca 2+ ] i increase was mediated by L and N type voltage sensitive calcium channels (VSCC) in NG 108 15 cells. CONCLUSION: Nicardipine at micromolar range inhibited both L and N type VSCC in dbcAMP differentiated NG 108 15 cells whereas nifedipine mainly inhibited L type calcium channels.