Sphingosine metabolism induces Ca2+ oscillations in rat pancreatic acinar cells

J Biol Chem. 1993 Jun 15;268(17):12353-8.


The possibility that sphingosine or a related metabolite could mediate inositol-1,4,5-triphosphate (1,4,5-IP3)-independent Ca2+ release in pancreatic acinar cells was investigated. In intact rat pancreatic acini superfused at 37 degrees C, sphingosine (10-100 microM) evoked, after a delay of several minutes, an increase in the cytosolic [Ca2+]i which was oscillatory below concentrations of 50 microM. At room temperature no increase in [Ca2+]i was observed. The increase in [Ca2+]i evoked by sphingosine was not inhibited by U73122, and thus was unlikely to be due to phosphatidylinositol (PI) hydrolysis. Furthermore, no PI hydrolysis or 1,4,5-IP3 production was detected on incubation with sphingosine. As metabolism of sphingosine could explain the temperature-dependent action, the effects of sphingosine and related sphingoid bases were tested in permeabilized cells. After a delay of 30 s at 37 degrees C, sphingosine evoked a slow increase in [Ca2+] into the medium. In contrast, addition of sphingosylphosphorylcholine (SPC) resulted in a rapid increase in [Ca2+]. This response was mimicked by 1,4,5-IP3 but not by addition of sphingosine phosphate (1-10 microM), ceramide (30 microM), or sphingomyelin (50 micrograms/ml). SPC appeared to induce release of Ca2+ from the same store as 1,4,5-IP3, as SPC failed to evoke any further increase in Ca2+ from cells previously depleted by addition of a maximal concentration of 2,4,5-IP3 or thapsigargin. 1,4,5-IP3 but not SPC-induced Ca2+ release was blocked by heparin, indicating that SPC-induced Ca2+ release was not mediated through the IP3 receptor-channel complex. This study demonstrates that SPC, a sphingosine metabolite, could be responsible for IP3-independent Ca2+ oscillations previously seen in pancreatic acinar cells.

Publication types

  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Animals
  • Calcium / metabolism*
  • Cholecystokinin / pharmacology
  • Estrenes / pharmacology
  • Fluorescent Dyes
  • Fura-2 / analogs & derivatives
  • In Vitro Techniques
  • Inositol 1,4,5-Trisphosphate / metabolism
  • Inositol Phosphates / metabolism*
  • Kinetics
  • Male
  • Oscillometry
  • Pancreas / metabolism*
  • Phosphatidylinositols / metabolism
  • Pyrrolidinones / pharmacology
  • Rats
  • Rats, Sprague-Dawley
  • Sphingosine / metabolism*
  • Sphingosine / pharmacology*
  • Time Factors
  • Type C Phospholipases / antagonists & inhibitors


  • Estrenes
  • Fluorescent Dyes
  • Inositol Phosphates
  • Phosphatidylinositols
  • Pyrrolidinones
  • fura-2-am
  • 1-(6-((3-methoxyestra-1,3,5(10)-trien-17-yl)amino)hexyl)-1H-pyrrole-2,5-dione
  • Inositol 1,4,5-Trisphosphate
  • Cholecystokinin
  • Type C Phospholipases
  • Sphingosine
  • Calcium
  • Fura-2