title: 3,4-Diaminopyridine induced hydrolysis of phosphoinositide in cultured neurons from embryo chick forebrain.
abstract: The effect of 3,4-diaminopyridine (DAP) on phosphoinositide hydrolysis in cultured neurons from embryo chick forebrain has been studied. DAP produced a dose- and time-dependent accumulation of inositol phosphates. At 1 mM DAP a maximal effect was obtained. In Ca2+ free medium, DAP-activated turnover of phosphoinositide was reduced, but was still significant. Blocking Ca2+ entry with 200 microM Cd2+ also did not abolish the DAP-induced accumulation of inositol phosphates. As a comparison the effect of high K+ exposure was investigated. High K+ enhanced phosphoinositide hydrolysis, and this effect was also reduced by excluding Ca2+ influx. Moreover, DAP had no additional effect on the high K(+)-induced hydrolysis of phosphoinositide. Using oxonol-V, a depolarization of the membrane potential was seen in the neurons bathed in DAP containing medium. It is suggested that the depolarization may play a role in DAP-activated phosphoinositide turnover in cultured neurons of the embryo chick forebrain, but that Ca2+ entry is not necessary for this effect.
authors.affiliation: Shanghai Institute of Physiology, Chinese Academy of Sciences.
authors.forename: Z
authors.initials: Z
authors.lastname: Dong
authors.forename: P H
authors.initials: PH
authors.lastname: Zhu
mesh_terms: D015761:4-Aminopyridine / Q000031:analogs & derivatives* / Q000494:pharmacology; D000077770:Amifampridine; D000818:Animals; D002478:Cells, Cultured; D002642:Chick Embryo; D003470:Culture Media; D006868:Hydrolysis; D008564:Membrane Potentials / Q000187:drug effects; D009474:Neurons / Q000187:drug effects / Q000378:metabolism*; D010716:Phosphatidylinositols / Q000378:metabolism*; D011188:Potassium / Q000494:pharmacology; D015221:Potassium Channels / Q000187:drug effects* / Q000378:metabolism*; D016548:Prosencephalon / Q000166:cytology / Q000187:drug effects / Q000378:metabolism*
chemical_list: D003470:Culture Media; D010716:Phosphatidylinositols; D015221:Potassium Channels; D015761:4-Aminopyridine; D000077770:Amifampridine; D011188:Potassium