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TRPC6 channels stimulated by angiotensin II are inhibited by TRPC1/C5 channel activity through a Ca 2+ ‐ and PKC‐dependent mechanism in native vascular myocytes
Author(s) -
Shi J.,
Ju M.,
Saleh S. N.,
Albert A. P.,
Large W. A.
Publication year - 2010
Publication title -
the journal of physiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.802
H-Index - 240
eISSN - 1469-7793
pISSN - 0022-3751
DOI - 10.1113/jphysiol.2010.194621
Subject(s) - trpc6 , trpc1 , trpc , bapta , chemistry , angiotensin ii , vascular smooth muscle , intracellular , transient receptor potential channel , biophysics , protein kinase c , trpc3 , extracellular , endocrinology , phosphorylation , biochemistry , receptor , biology , smooth muscle
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 m m BAPTA), 1 n m and 10 n m 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 n m 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 n m 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 m m BAPTA), 10 n m 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 n m Ang II‐evoked TRPC6 channel activity in inside‐out patches. Moreover, in zero external Ca 2+ (0 [Ca 2+ ] o ) 100 n m 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 n m 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.