Nimodipine and nitrendipine inhibit N-type calcium channels in dibutyryl cAMP-differentiated neuroblastoma x glioma hybrid (NG 108-15) cells.
The effects of nifedipine, niguldipine, nimodipine and nitrendipine on the high K+-induced intracellular Ca2+ ([Ca2+]i) transient in dibutyryl cAMP-differentiated neuroblastoma x glioma hybrid NG 108-15 cells were studied by using the fluorescent Ca2+ indicator fura-2. It was observed that nifedipine at the concentration of 50 microM inhibited the high K+-induced [Ca2+]i transient by about 60%; niguldipine at the concentration of 10 microM caused a reduction of about 65% in the high K+-induced calcium signal and a further increase in the concentration up to 50 microM did not result in a significant further reduction in the high K+-induced calcium signal. However, on the other hand, nimodipine and nitrendipine at 50 microM inhibited almost completely the high K+-induced [Ca2+]i transient. Consequently, it was demonstrated in the present study that nimodipine and nitrendipine inhibit both L- and N-type calcium channels and thus seem to be unique among the dihydropyridines examined in their effects on calcium channels in dibutyryl cAMP-differentiated neuroblastoma x glioma hybrid NG 108-15 cells, whereas nifedipine and niguldipine appear to block mainly L-type calcium channels.
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Institute of Pharmacology and Toxicology, Dresden University of Technology, Germany.
Bräter
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Andreas
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D000818:Animals; D003994:Bucladesine / Q000494:pharmacology*; D002118:Calcium / Q000378:metabolism; D002121:Calcium Channel Blockers / Q000494:pharmacology*; D015220:Calcium Channels / Q000187:drug effects / Q000502:physiology*; D002454:Cell Differentiation / Q000187:drug effects*; D004095:Dihydropyridines / Q000494:pharmacology; D005071:Evoked Potentials / Q000187:drug effects; D005910:Glioma; D006822:Hybrid Cells; D007700:Kinetics; D051379:Mice; D009447:Neuroblastoma; D009553:Nimodipine / Q000494:pharmacology*; D009568:Nitrendipine / Q000494:pharmacology*; D011188:Potassium / Q000494:pharmacology; D051381:Rats
D002121:Calcium Channel Blockers; D015220:Calcium Channels; D004095:Dihydropyridines; D009553:Nimodipine; D003994:Bucladesine; D009568:Nitrendipine; D011188:Potassium; D002118:Calcium; C054074:niguldipine