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Cardiovasc Res. 2014 Oct 1;104(1):138-46. doi: 10.1093/cvr/cvu190. Epub 2014 Aug 18.

Nitric oxide and protein kinase G act on TRPC1 to inhibit 11,12-EET-induced vascular relaxation.

Author information

1
School of Biomedical Sciences and Li Ka Shing institute of Health Science, The Chinese University of Hong Kong, Hong Kong, China Shenzhen Research Institute, The Chinese University of Hong Kong, Shenzhen, China.
2
School of Biomedical Sciences and Li Ka Shing institute of Health Science, The Chinese University of Hong Kong, Hong Kong, China.
3
Stem Cell and Regenerative Medicine Consortium, The University of Hong Kong, Hong Kong, China.
4
Department of Surgery, The Chinese University of Hong Kong, Hong Kong, China.
5
School of Biomedical Sciences and Li Ka Shing institute of Health Science, The Chinese University of Hong Kong, Hong Kong, China Shenzhen Research Institute, The Chinese University of Hong Kong, Shenzhen, China yao2068@cuhk.edu.hk.

Abstract

AIMS:

Vascular endothelial cells synthesize and release vasodilators such as nitric oxide (NO) and epoxyeicosatrienoic acids (EETs). NO is known to inhibit EET-induced smooth muscle hyperpolarization and relaxation. This study investigates the underlying mechanism of this inhibition.

METHODS AND RESULTS:

Through measurements of membrane potential and arterial tension, we show that 11,12-EET induced membrane hyperpolarization and vascular relaxation in endothelium-denuded porcine coronary arteries. These responses were suppressed by S-nitroso-N-acetylpenicillamine (SNAP) and 8-Br-cGMP, an NO donor and a membrane-permeant analogue of cGMP, respectively. The inhibitory actions of SNAP and 8-Br-cGMP on 11,12-EET-induced membrane hyperpolarization and vascular relaxation were reversed by hydroxocobalamin, an NO scavenger; ODQ, a guanylyl cyclase inhibitor; and KT5823, a protein kinase G (PKG) inhibitor. The inhibitory actions of SNAP and 8-bromo cyclic GMP (8-Br-cGMP) on the EET responses were also abrogated by shielding TRPC1-PKG phosphorylation sites with an excessive supply of exogenous PKG substrates, TAT-TRPC1(S172) and TAT-TRPC1(T313). Furthermore, a phosphorylation assay demonstrated that PKG could directly phosphorylate TRPC1 at Ser(172) and Thr(313). In addition, 11,12-EET failed to induce membrane hyperpolarization and vascular relaxation when TRPV4, TRPC1, or KCa1.1 was selectively inhibited. Co-immunoprecipitation studies demonstrated that TRPV4, TRPC1, and KCa1.1 physically associated with each other in smooth muscle cells.

CONCLUSION:

Our findings demonstrate a novel role of the NO-cGMP-PKG pathway in the inhibition of 11,12-EET-induced smooth muscle hyperpolarization and relaxation via PKG-mediated phosphorylation of TRPC1.

KEYWORDS:

Epoxyeicosatrienoic acids; Nitric oxide; TRP channels; Vascular relaxation

PMID:
25139746
DOI:
10.1093/cvr/cvu190
[Indexed for MEDLINE]

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