Sodium ion and the neutrotransmitter-stimulated 32P labelling of phosphoinositides and other phospholipids in the iris muscle

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Abstract

The effects of Na+, other cations and the neurotransmitters, acetylcholine and norepinephrine on 32Pi incorporation into phospholipids of the rabbit iris smooth muscle were investigated [1]. The basal 32P-labelling of phospholipids, including phosphatidic acid, phosphatidylinositol, phosphatidylcholine, phosphatidylethanolamine and the polyphosphoinositides increased with Na+ concentration [2]. The neurotransmitter-stimulated 32P-labelling of phosphotidic acid, phosphatidylinositol and phosphatidylcholine is dependent on the presence of extracellular Na+ [3]. The monovalent cation requirement for Na+ is specific. Of the monovalent cations Li+, NH4+, K+, choline+ and Tris, only Li+ partially substituted for Na+ [4]. A significant decrease in 32P labelling of phospholipids in response to acetylcholine was observed when Ca2+ and/or K+ were added to an isoosmotic medium deficient of Na+ [5]. Ouabain, which blocks the Na+-pump, inhibited the basal 32Pi incorporation into phosphatidylcholine and the acetylcholine-stimulated 32P labelling of phosphatidic acid, phosphatidylinositol and phosphatidylcholine [6]. It was suggested that phosphoinositide breakdown is associated with Ca2+ influx as we have previously reported (Akhtar, R.A. and Abdel-Latif, A.A. (1978) J. Pharmacol. Exp. Ther. 204, 655–668) and that the enhanced 32P-labelling of phosphoinositides could be associated with Na+ outflux, via the Na+-pump mechanism.

References (30)

  • R.H. Michell

    Biochim. Biophys. Acta

    (1975)
  • A.A. Abdel-Latif et al.
  • H.D. Griffin et al.

    Biochem. Pharmacol.

    (1979)
  • R.A. Akhtar et al.

    Gen. Pharmacol.

    (1979)
  • A.A. Abdel-Latif et al.

    Biochim. Biophys. Acta

    (1980)
  • R.A. Akhtar et al.

    Biochim. Biophys. Acta

    (1978)
  • L.E. Hokin et al.

    Int. Rev. Neurobiol.

    (1960)
  • G. Keryer et al.

    FEBS Lett.

    (1979)
  • Hokin-Neaverson

    Biochem. Biophys. Res. Commun.

    (1974)
  • J.N. Hawthorne et al.

    J. Neurochem.

    (1979)
  • S.S. Jafferji et al.

    Biochem. J.

    (1976)
  • J.W. Putney

    Pharmacol. Rev.

    (1979)
  • A.A. Abdel-Latif
  • A.A. Abdel-Latif et al.

    Biochem. J.

    (1977)
  • R.A. Akhtar et al.

    J. Pharmacol. Exp. Ther.

    (1978)
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