ミドリカワ ミツハル
  緑川 光春
   所属   医学部 医学科
   職種   講師
論文種別 原著
言語種別 英語
査読の有無 査読あり
表題 Increase in the pool size of releasable synaptic vesicles by the activation of protein kinase C in goldfish retinal bipolar cells.
掲載誌名 正式名:The Journal of neuroscience : the official journal of the Society for Neuroscience
略  称:J Neurosci
ISSNコード:(1529-2401)0270-6474(Linking)
掲載区分国外
巻・号・頁 22(12),4776-4785頁
著者・共著者 Berglund Ken, Midorikawa Mitsuharu, Tachibana Masao
発行年月 2002/06
概要 Secretion from neurons and neuroendocrine cells is enhanced by the activation of protein kinase C (PKC) in various preparations. We have already reported that transmitter (glutamate) release from Mb1 bipolar cells in the goldfish retina is potentiated by the activation of PKC. However, it is not yet settled whether the potentiation is ascribed to the increase in the pool size of releasable synaptic vesicles or in release probability. In the present study, Ca2+ influx and exocytosis were simultaneously monitored by measuring the presynaptic Ca2+ current and membrane capacitance changes, respectively, in a terminal detached from the bipolar cell. The double pulse protocol was used to estimate separately the changes in the pool size and release probability. The activation of PKC by phorbol 12-myristate 13-acetate (PMA) specifically increased the pool size but not the release probability. PKC was activated by PMA even after the Ca2+ influx was blocked by Co2+. In bipolar cells the releasable pool can be divided into two components: one is small and rapidly exhausted, and the other is large and slowly exocytosed. To identify which component is responsible for the increase in the pool size, the effects of PMA and a PKC-specific inhibitor, bisindolylmaleimide I (BIS), on each component were examined. The slow component was selectively increased by PMA and reduced by BIS. Thus, we conclude that the activation of PKC in Mb1 bipolar cells potentiates glutamate release by increasing the pool size of the slow component.
PMID 12077174