The synthesis of 20-HETE in small porcine coronary arteries antagonizes EDHF-mediated relaxation.
OBJECTIVE
Exogenous application of 20-hydroxyeicosatetraenoic acid (20-HETE) to small (300-500 microm) porcine coronary arteries elicits contraction by activating the Rho kinase and increasing the sensitivity of contractile proteins to Ca2+. Here, we determined whether 20-HETE is involved in the regulation of coronary artery tone as well as its role in the modulation of endothelium-derived hyperpolarizing factor (EDHF)-mediated responses.


RESULTS
Small porcine coronary arteries expressed cytochrome P450 (CYP) 4A, as demonstrated by Western blot analysis, and generated 20-HETE. Moreover, 20-HETE production was increased two- and threefold over basal levels in response to isometric stretch or the thromboxane analogue U46619, respectively, and was inhibited by the CYP 4A inhibitor N-methylsulfonyl-12,12-dibromododec-11-enamide (DDMS). In vascular reactivity studies, DDMS attenuated U46619-induced contractions and induced a concentration-dependent but endothelium-independent relaxation of precontracted arterial rings. Endogenously generated 20-HETE significantly inhibited the EDHF-mediated relaxation of coronary arteries, which was potentiated by the phospholipase A2 inhibitors AACOCF3 and ONO-RS-082, as well as by the omega-hydroxylase inhibitors 17-octadecynoic acid and DDMS. EDHF-mediated relaxation was not affected by either the nonselective epoxygenase inhibitors miconazole and clotrimazole or the CYP 2C inhibitor sulfaphenazole but was abolished by the Na-K-ATPase inhibitor, ouabain. Exogenous application of 20-HETE inhibited EDHF-mediated relaxations and caused a concomitant increase in the phosphorylation of protein kinase Calpha (PKCalpha). This effect was reversed by the PKC inhibitor Ro-318220 and mimicked by the PKC activator phorbol-12 myristate 13-acetate.


CONCLUSIONS
These results indicate that vascular tone in small porcine coronary arteries is partly determined by the endogenous production of 20-HETE. In addition, 20-HETE functionally antagonizes EDHF-mediated relaxation via a PKCalpha-dependent mechanism, probably involving the inhibition of the Na-K-ATPase.
Randriamboavonjy
Voahanginirina
V
Vascular Signalling Group, Institut für Kardiovaskuläre Physiologie, Johann Wolfgang Goethe-Universität, Theodor-Stern-Kai 7, D-60590 Frankfurt am Main, Germany.
Kiss
Ladislau
L
Falck
John R
JR
Busse
Rudi
R
Fleming
Ingrid
I
D019796:15-Hydroxy-11 alpha,9 alpha-(epoxymethano)prosta-5,13-dienoic Acid / Q000494:pharmacology; D000577:Amides / Q000494:pharmacology; D000818:Animals; D001189:Aryl Hydrocarbon Hydroxylases / Q000378:metabolism; D001685:Biological Factors / Q000494:pharmacology*; D003331:Coronary Vessels / Q000187:drug effects / Q000378:metabolism*; D000072470:Cytochrome P450 Family 4; D004305:Dose-Response Relationship, Drug; D006893:Hydroxyeicosatetraenoic Acids / Q000096:biosynthesis* / Q000494:pharmacology; D066298:In Vitro Techniques; D006899:Mixed Function Oxygenases / Q000378:metabolism; D011493:Protein Kinase C / Q000037:antagonists & inhibitors / Q000378:metabolism; D013450:Sulfones / Q000494:pharmacology; D013552:Swine; D013755:Tetradecanoylphorbol Acetate / Q000494:pharmacology; D014662:Vasoconstrictor Agents / Q000494:pharmacology; D014665:Vasodilator Agents / Q000494:pharmacology*
D000577:Amides; D001685:Biological Factors; D006893:Hydroxyeicosatetraenoic Acids; D013450:Sulfones; D014662:Vasoconstrictor Agents; D014665:Vasodilator Agents; C067410:endothelium-dependent hyperpolarization factor; D019796:15-Hydroxy-11 alpha,9 alpha-(epoxymethano)prosta-5,13-dienoic Acid; C055987:20-hydroxy-5,8,11,14-eicosatetraenoic acid; C117975:DDMS; D006899:Mixed Function Oxygenases; D001189:Aryl Hydrocarbon Hydroxylases; D000072470:Cytochrome P450 Family 4; C436964:cytochrome P-450 CYP4A4 (rabbit); D011493:Protein Kinase C; D013755:Tetradecanoylphorbol Acetate