Identification and metabolism of polyphosphoinositides in isolated islets of Langerhans

The results suggest that the Ca2+-dependent breakdown of polyphosphoinositides in an early metabolic event during the initiation of insulin release

S G Laychock


Scholarcy highlights

  • Isolated islets were incubated withP1 and radiolabelling of polyphosphoinositides were determined
  • The results show that catabolism of islet polyphosphoinositides is responsive to various stimuli of insulin secretion
  • The spots containing the polyphosphoinositides remained as single spots and retained the level of radioactivity obtained after one-dimensional development when the plates were subsequently developed in a second-dimension using the solvent system chloroform/methanol/acetic acid/water
  • D-galactose, which is not a secretagogue in islets, did not show the polyphosphoinositide effect characterized by glucose stimulation
  • The effects of glucose on the breakdown of islet polyphosphoinositides were modulated by Ca2, since the inhibition of lipid breakdown by the Ca2+-chelating agent EGTA was partially reversed by Ca2+ addition
  • The present studies demonstrating that insulin secretagogues provoke the breakdown of polyphosphoinositides are reminiscent of a similar phospholipid effect in other secretory cells

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