Phosphoinositide 3-kinase gamma mediates angiotensin II-induced stimulation of L-type calcium channels in vascular myocytes

J Biol Chem. 2001 Aug 31;276(35):32545-51. doi: 10.1074/jbc.M102582200. Epub 2001 Jul 6.


Previous results have shown that in rat portal vein myocytes the betagamma dimer of the G(13) protein transduces the angiotensin II-induced stimulation of calcium channels and increase in intracellular Ca(2+) concentration through activation of phosphoinositide 3-kinase (PI3K). In the present work we determined which class I PI3K isoforms were involved in this regulation. Western blot analysis indicated that rat portal vein myocytes expressed only PI3Kalpha and PI3Kgamma and no other class I PI3K isoforms. In the intracellular presence of an anti-p110gamma antibody infused by the patch clamp pipette, both angiotensin II- and Gbetagamma-mediated stimulation of Ca(2+) channel current were inhibited, whereas intracellular application of an anti-p110alpha antibody had no effect. The anti-PI3Kgamma antibody also inhibited the angiotensin II- and Gbetagamma-induced production of phosphatidylinositol 3,4,5-trisphosphate. In Indo-1 loaded cells, the angiotensin II-induced increase in [Ca(2+)](i) was inhibited by intracellular application of the anti-PI3Kgamma antibody, whereas the anti-PI3Kalpha antibody had no effect. The specificity of the anti-PI3Kgamma antibody used in functional experiments was ascertained by showing that this antibody did not recognize recombinant PI3Kalpha in Western blot experiments. Moreover, anti-PI3Kgamma antibody inhibited the stimulatory effect of intracellularly infused recombinant PI3Kgamma on Ca(2+) channel current without altering the effect of recombinant PI3Kalpha. Our results show that, although both PI3Kgamma and PI3Kalpha are expressed in vascular myocytes, the angiotensin II-induced stimulation of vascular L-type calcium channel and increase of [Ca(2+)](i) involves only the PI3Kgamma isoform.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Angiotensin II / pharmacology*
  • Animals
  • Antibodies / pharmacology
  • Barium / pharmacology
  • Blotting, Western
  • Calcium / metabolism
  • Calcium Channels, L-Type / drug effects
  • Calcium Channels, L-Type / physiology*
  • Cell Membrane / drug effects
  • Cell Membrane / enzymology
  • Cell Membrane / physiology
  • Class Ib Phosphatidylinositol 3-Kinase
  • In Vitro Techniques
  • Isoenzymes / isolation & purification
  • Isoenzymes / metabolism*
  • Kinetics
  • Membrane Potentials / drug effects
  • Membrane Potentials / physiology
  • Microsomes / enzymology
  • Muscle, Smooth, Vascular / cytology
  • Muscle, Smooth, Vascular / drug effects
  • Muscle, Smooth, Vascular / physiology*
  • Patch-Clamp Techniques
  • Phorbol 12,13-Dibutyrate / pharmacology
  • Phosphatidylinositol 3-Kinases / isolation & purification
  • Phosphatidylinositol 3-Kinases / metabolism*
  • Portal Vein / physiology
  • Protein Subunits
  • Rats
  • Recombinant Proteins / metabolism


  • Antibodies
  • Calcium Channels, L-Type
  • Isoenzymes
  • Protein Subunits
  • Recombinant Proteins
  • Angiotensin II
  • Barium
  • Phorbol 12,13-Dibutyrate
  • Phosphatidylinositol 3-Kinases
  • Class Ib Phosphatidylinositol 3-Kinase
  • Pik3cg protein, rat
  • Calcium