Details

Autor(en) / Beteiligte

• Whitham, Emma M.
• Challiss, R.A. John
• Nahorski, Stefan R.

Titel

Inositol 1,4,5‐trisphosphate‐stimulated calcium release from permeabilized cerebellar granule cells

Ist Teil von

• British journal of pharmacology, 1991-09, Vol.104 (1), p.202-206

Ort / Verlag

Oxford, UK: Blackwell Publishing Ltd

Erscheinungsjahr

1991

Quelle

EZB Electronic Journals Library

Beschreibungen/Notizen

• 1 Muscarinic cholinoceptor stimulation of phosphoinositide hydrolysis in rat cultured cerebellar granule cells results in a rapid, transient accumulation of inositol 1,4,5‐trisphosphate (Ins(1,4,5)P3), which has been implicated in the release of non‐mitochondrial intracellular Ca2+stores. In the present study, the release of Ca2+from intracellular stores and the Ins(1,4,5)P3 receptor responsible for this process have been investigated. 2 Monolayers of saponin‐permeabilized granule cells accumulate 45Ca2+in an ATP‐dependent manner and the sequestered 45Ca2+can be concentration‐dependently released by Ins(1,4,5)P3 by a stereospecific and heparin‐sensitive mechanism. The EC50 for Ins(1,4,5)P3‐stimulated 45Ca2+release was 80 ± 3 nm. 3 Radioligand binding studies performed on a crude granule cell membrane fraction indicated the presence of an apparently homogeneous population of stereo‐specific Ins(1,4,5)P3 receptors (KD 54.7 ± 2.0 nm; Bmax 1.37 ± 0.29 pmol mg−1 protein). 4 This study provides evidence for Ins(1,4,5)P3‐sensitive intracellular Ca2+stores in primary cultures of cerebellar granule cells and suggest that these cells provide an excellent model neuronal system in which to study the relative functional roles of Ca2+release from intracellular stores and Ca2+‐entry in neuronal Ca2+homeostasis.