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Sphingosine kinase functionally links elevated transmural pressure and increased reactive oxygen species formation in resistance arteries
Author(s) -
Keller Matthias,
Lidington Darcy,
Vogel Lukas,
Peter Bernhard Friedrich,
Sohn HaeYoung,
Pagano Patrick J.,
Pitson Stuart,
Spiegel Sarah,
Pohl Ulrich,
Bolz SteffenSebastian
Publication year - 2006
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fj.05-4075fje
Subject(s) - nadph oxidase , reactive oxygen species , vasoconstriction , rhoa , microbiology and biotechnology , sphingosine kinase , chemistry , sphingosine , rho associated protein kinase , biochemistry , signal transduction , biology , sphingosine 1 phosphate , endocrinology , receptor
ABSTRACT Myogenic vasoconstriction, an intrinsic response to elevated transmural pressure (TMP), requires the activation of sphingosine kinase (Sk1) and the generation of reactive oxygen species (ROS). We hypothesized that pressure‐induced Sk1 signaling and ROS generation are functionally linked. Using a model of cannulated resistance arteries isolated from the hamster gracilis muscle, we monitored vessel diameter and smooth muscle cell (SMC) Ca 2+ i (Fura‐2) or ROS production (dichlorodihydrofluorescein). Elevation of TMP stimulated the translocation of a GFP‐tagged Sk1 fusion protein from the cytosol to the plasma membrane, indicative of enzymatic activation. Concurrently, elevation of TMP initiated a rapid and transient production of ROS, which was enhanced by expression of wild‐type Sk1 (hSk wt ) and inhibited by its dominant‐negative mutant (hSk G82D ). Exogenous sphingosine‐1‐phosphate (S1P) also stimulated ROS generation is isolated vessels. Chemical (1μmol/L DPI), peptide (gp91ds‐ tat /gp91ds), and genetic (N17Rac) inhibition strategies indicated that NADPH oxidase was the source of the pressure‐induced ROS. NADPH oxidase inhibition attenuated myogenic vasoconstriction and reduced the apparent Ca 2+ sensitivity of the SMC contractile apparatus, without affecting Ca 2+ ‐independent, RhoA‐mediated vasoconstriction in response to exogenous S1P. Our results indicate a mandatory role for Sk1/S1P in mediating pressure‐induced, NADPH oxidase‐derived ROS formation. In turn, ROS generation appears to increase Ca 2+ sensitivity, necessary for full myogenic vasoconstriction.