Evidence that quantal Ca2+ release in HSG cells is not due to 'all-or-none' release from discrete Ca2+ stores with differing sensitivities to IP3

A. Moran, R. James Turner

Research output: Contribution to journalArticlepeer-review

1 Scopus citations


We demonstrate that the application of the muscarinic agonist carbachol to the human salivary epithelial cell line HSG elicits the now well-known phenomenon of 'quantal' Ca2+-release; namely, that the application of a submaximal concentration of agonist results in the release of only a portion of the agonist-sensitive intracellular Ca2+ pool. One explanation that has been proposed to account for this effect is that there are multiple intracellular Ca2+ stores, each with a different agonist sensitivity, which release Ca2+ in an 'all-or-none' fashion. We test this hypothesis in intact HSG cells with an experimental protocol designed to preferentially load less-agonist-sensitive stores with 45Ca2+ and more-agonist-sensitive stores with 45Ca2+. However, contrary to the expectations of the above explanation, these cells do not preferentially release 45Ca2+ in response to low concentrations of agonist. Thus our data suggest that quantal Ca2+ release must arise from some other property of the stores or their Ca2+ release channels.

Original languageEnglish
Pages (from-to)53-56
Number of pages4
JournalMolecular and Cellular Biochemistry
Issue number1
StatePublished - 1 Sep 1979


  • Ca release
  • IP receptor
  • quantal Ca release
  • stimulus secretion coupling


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