Muscarinic receptor-induced phosphoinositide hydrolysis at resting cytosolic Ca2+ concentration in PC12 cells

L. M. Vicentini, A. Ambrosini, F. Di Virgilio, T. Pozzan, J. Meldolesi

Research output: Contribution to journalArticlepeer-review


In PC12 cells, cultured in the presence of nerve growth factor to increase their complement of muscarinic receptors, treatment with carbachol induces muscarinic receptor-dependent rises in free cytosolic Ca2+ as well as hydrolysis of membrane phosphoinositides. Experiments were carried out to clarify the relationship between these two receptor-triggered events. In particular, since inositol-1,4,5-triphosphate (the hydrophilic metabolite produced by the hydrolysis of phosphatidylinositol-4,5-bisphosphate) is believed to mediate intracellularly the release of Ca2+ from nonmitochondrial store(s), it was important to establish whether it can be generated at resting cytoplasmic concentration of Ca2+ (~ 0.1 μM). Cells incubated in Ca2+-free medium were depleted of their cytoplasmic Ca2+ stores by pretreatment with ionomycin. When these cells were then treated with carbachol, their cytosolic concentration of Ca2+ remained at the resting level, whereas inositol-1,4,5-trisphosphate generation was still markedly stimulated. Our results demonstrate that an increase in the concentration of cytosolic Ca2+ is not a necessary intermediate between receptor activation and phosphoinositide hydrolysis, and therefore support the second-messenger role of inositol-1,4,5-trisphosphate.

Original languageEnglish
Pages (from-to)1330-1333
Number of pages4
JournalJournal of Cell Biology
Issue number4
Publication statusPublished - 1985

ASJC Scopus subject areas

  • Cell Biology


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