Article date: September 1991
By: Emma M. Whitham, R.A. John Challiss, Stefan R. Nahorski, in Volume 104, Issue 1, pages 202-206
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.
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.
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).
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.
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.
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.
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).
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.
DOI: 10.1111/j.1476-5381.1991.tb12408.x
View this article