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Different Role of Epoxyeicosatrienoic Acids (EET 11,12 ) in Endothelium‐Derived Hyperpolarizing Factor‐Mediated Relaxation in Porcine Coronary and Pulmonary Micro‐Arteries
Author(s) -
Zou Wei,
Yang Qin,
Yim Anthony P. C.,
He GuoWei
Publication year - 2002
Publication title -
journal of cardiac surgery
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.428
H-Index - 58
eISSN - 1540-8191
pISSN - 0886-0440
DOI - 10.1046/j.1540-8191.2002.101433.x
Subject(s) - coronary arteries , medicine , bradykinin , myograph , pulmonary artery , cardiology , nitric oxide , endothelium derived hyperpolarizing factor , apamin , artery , vasodilation , potassium channel , charybdotoxin , receptor
Objectives:Endothelium‐derived hyperpolarizing factor (EDHF) plays a key role in vasorelaxation and the cytochrome P450‐monooxygenase metabolites of arachidonic acid epoxyeicosatrienoic acids (EETs), such as EET 11,12, have been suggested to be EDHF in various vasculatures. However, little is known about the role of EET 11,12 in the coronary and pulmonary circulation, especially in microcirculation. The present study was designed to examine the role of EET 11,12 in porcine coronary and pulmonary micro‐arteries. Methods: Porcine coronary and pulmonary micro‐arteries (diameter 200‐450 μm) were studied in a myograph ( n = 8 in each group). The artery rings were set at the 90% of the circumference at 100 mm Hg for coronary or 30 mm Hg for pulmonary micro‐arteries, respectively. After precontraction with U 46619 (−8.2 log M for coronary and −7.5 log M for pulmonary micro‐arteries), EET 11,12 (−10 ∼−6.5 log M) or bradykinin (BK, −10 ∼−6.5 log M)‐induced relaxation was established in the presence of inhibitors for cyclooxygenase (indomethacin, 7 μM), nitric oxide (NO) synthetase ( N G ‐nitro‐ L ‐arginine, 300 μM), and NO scavenger oxyhemoglobin (20 μM). Results: EET 11,12 induced a dose‐dependent relaxation in coronary micro‐arteries with the maximal relaxation of 18.3 ± 3.3% that was significantly less than the relaxation induced by BK (72.5 ± 7.8%; P < 0.001) . In contrast, in pulmonary micro‐arteries, BK induced a marked relaxation (69.6 ± 6.3%) whereas EET 11,12 did not have any effect. Conclusion: In porcine coronary micro‐arteries, EET 11,12 may partially mimic the action of EDHF whereas in pulmonary arteries, this substance is unlikely involved in the EDHF‐mediated relaxation.