期刊
AMERICAN JOURNAL OF PHYSIOLOGY-HEART AND CIRCULATORY PHYSIOLOGY
卷 295, 期 1, 页码 H89-H96出版社
AMER PHYSIOLOGICAL SOC
DOI: 10.1152/ajpheart.00054.2008
关键词
endothelium-derived hyperpolarizing factor; arachidonic acid; vasodilation; mean arterial pressure
资金
- NHLBI NIH HHS [R01 HL037981-20, HL-37981, R01 HL037981] Funding Source: Medline
Arachidonic acid (AA) metabolites from the 15-lipoxygenase-1 (15-LO-1) pathway, trihydroxyeicosatrienoic acids (THETAs) and hydroxy-epoxyeicosatrienoic acids (HEETAs), are endothelium-derived hyperpolarizing factors (EDHFs) and relax rabbit arteries. Rabbit vascular 15-LO-1 expression, THETA and HEETA synthesis, and nitric oxide and prostaglandin-independent relaxations to acetylcholine (ACh) and AA decreased with age (neonates to 16-wk-old). We characterized age-dependent ACh-hypotensive responses in vivo in 1-, 4-, 8-, and 16-wk-old rabbits and the contribution of THETAs and HEETAs to these responses. In anesthetized rabbits, blood pressure responses to ACh (4-4,000 ng/kg) were determined in the presence of vehicle or various inhibitors. ACh responses decreased with age (P > 0.001). In the absence or presence of N-omega-nitro-L-arginine methyl ester (L-NAME) and indomethacin (Indo), maximum responses in 1 (-54.7 +/- 7.4 and -37.9 +/- 3.9%)-and 4 (-48.8 +/- 2.4 and -35.5 +/- 7.8%)wk- old rabbits were higher than 8 (-30.0 +/- 2.8 and -26.6 +/- 4.4%)and 16 (-36.7 +/- 3.5 and -27.3 +/- 10%)-wk-old rabbits. A lipoxygenase inhibitor, BW755C, reduced THETA and HEETA synthesis in mesenteric arteries. In the presence of Indo and N-omega-nitro-L-arginine, ACh relaxations were reduced by BW755C to a greater extent in the mesenteric arteries from the younger rabbits. In 4-wk-old rabbits treated with L-NAME and Indo, the maximum ACh hypotension was reduced by the potassium channel inhibitors apamin and charybdotoxin to-6.9 +/- 0.9%, by apamin alone to -19.5 +/- 1.4%, and by BW755C to -18.8 +/- 3.5%. The present study indicates that the age-related decrease in ACh-induced hypotension is mediated by the decreased synthesis of the 15-LO-1 metabolites THETAs and HEETAs.
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