Investigation of the relationship between cell surface calcium ion gating and phosphatidylinositol turnover by comparison of the effects of elevated extracellular potassium ion concentration on ileum smooth muscle and pancreas

Research output: Contribution to journalArticlepeer-review


Colleges, School and Institutes

External organisations

  • University of Birmingham


Incubation of fragments of guinea pig ileum smooth muscle in the presence of an elevated extracellular K+ concentration, which causes an increase in cell surface Ca2+ permeability and thus leads to contraction, caused a marked increase in phosphatidylinositol turnover, as assessed by incorporation of 32Pi. This response was not diminished by atropine or propylbenzilylcholine mustard, two muscarinic cholinergic antagonists, and was therefore not caused by the release of endogenous acetylcholine within the tissue. In contrast, exposure of guinea pig pancreas fragments to high extracellular [K+], which does not increase cell surface Ca2+ permeability or evoke secretion, did not cause an increase in phosphatidylinositol turnover, even though such an increase was triggered by carbamoylcholine, which is a secretagogue. These observations are consistent with a suggested function for phosphatidylinositol breakdown in the mechanisms of cell surface Ca2+ gates.


Original languageEnglish
Pages (from-to)397-399
Number of pages3
JournalBiochemical Journal
Issue number2
Publication statusPublished - 1 Jan 1976