TRPC6 channels stimulated by angiotensin II are inhibited by TRPC1/C5 channel activity through a Ca2+- and PKC-dependent mechanism in native vascular myocytes

J Physiol. 2010 Oct 1;588(Pt 19):3671-82. doi: 10.1113/jphysiol.2010.194621. Epub 2010 Jul 26.


The present work investigated interactions between TRPC1/C5 and TRPC6 cation channel activities evoked by angiotensin II (Ang II) in native rabbit mesenteric artery vascular smooth muscle cells (VSMCs). In low intracellular Ca(2+) buffering conditions (0.1 mm BAPTA), 1 nm and 10 nm Ang II activated both 2 pS TRPC1/C5 channels and 15-45 pS TRPC6 channels in the same outside-out patches. However, increasing Ang II to 100 nm abolished TRPC6 activity but further increased TRPC1/C5 channel activity. Comparison of individual patches revealed an inverse relationship between TRPC1/C5 and TRPC6 channel activity suggesting that TRPC1/C5 inhibits TRPC6 channel activity. Inclusion of anti-TRPC1 and anti-TRPC5 antibodies, raised against intracellular epitopes, in the patch pipette solution blocked TRPC1/C5 channel currents but potentiated by about six-fold TRPC6 channel activity evoked by 1-100 nm Ang II in outside-out patches. Bath application of T1E3, an anti-TRPC1 antibody raised against an extracellular epitope, also increased Ang II-evoked TRPC6 channel activity. With high intracellular Ca(2+) buffering conditions (10 mm BAPTA), 10 nm Ang II-induced TRPC6 channel activity was increased by about five-fold compared to channel activity with low Ca(2+) buffering. In addition, increasing intracellular Ca(2+) levels ([Ca(2+)](i)) at the cytosolic surface inhibited 10 nm Ang II-evoked TRPC6 channel activity in inside-out patches. Moreover, in zero external Ca(2+) (0 [Ca(2+)](o)) 100 nm Ang II induced TRPC6 channel activity in outside-out patches. Pre-treatment with the PKC inhibitor, chelerythrine, markedly increased TRPC6 channel activity evoked by 1-100 nm Ang II and blocked the inhibitory action of [Ca(2+)](i) on TRPC6 channel activity. Co-immunoprecipitation studies shows that Ang II increased phosphorylation of TRPC6 proteins which was inhibited by chelerythrine, 0 [Ca(2+)](o) and the anti-TRPC1 antibody T1E3. These results show that TRPC6 channels evoked by Ang II are inhibited by TRPC1/C5-mediated Ca(2+) influx and stimulation of PKC, which phosphorylates TRPC6 subunits. These conclusions represent a novel interaction between two distinct vasoconstrictor-activated TRPC channels expressed in the same native VSMCs.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Angiotensin II / pharmacology*
  • Animals
  • Antibodies, Blocking / pharmacology
  • Benzophenanthridines / pharmacology
  • Blotting, Western
  • Calcium / physiology*
  • Calcium Signaling / drug effects
  • Calcium Signaling / physiology
  • Egtazic Acid / analogs & derivatives
  • Egtazic Acid / pharmacology
  • Electrophysiological Phenomena
  • Enzyme Inhibitors / pharmacology
  • Immunoprecipitation
  • In Vitro Techniques
  • Muscle, Smooth, Vascular / physiology
  • Myocytes, Smooth Muscle / drug effects*
  • Myocytes, Smooth Muscle / physiology*
  • Patch-Clamp Techniques
  • Protein Kinase C / antagonists & inhibitors
  • Protein Kinase C / physiology*
  • Rabbits
  • Stimulation, Chemical
  • TRPC Cation Channels / drug effects*
  • Vasoconstrictor Agents / pharmacology*


  • Antibodies, Blocking
  • Benzophenanthridines
  • Enzyme Inhibitors
  • TRPC Cation Channels
  • Vasoconstrictor Agents
  • transient receptor potential cation channel, subfamily C, member 1
  • Angiotensin II
  • Egtazic Acid
  • chelerythrine
  • Protein Kinase C
  • 1,2-bis(2-aminophenoxy)ethane-N,N,N',N'-tetraacetic acid
  • Calcium