Ballard Kevin D, Tschakovsky Michael E, Zaleski Amanda L, Polk Donna M, Thompson Paul D, Kiernan Francis J, Parker Beth A
Division of Cardiology, Hartford Hospital, 80 Seymour Street, Hartford, CT 06102, USA.
School of Kinesiology and Health Studies, Queen's University, 28 Division Street, Kingston, ON, Canada K7L 3N6.
J Aging Res. 2014;2014:876125. doi: 10.1155/2014/876125. Epub 2014 May 21.
Background. Blocking nitric oxide (NO) and vasodilator prostanoids (PN) does not consistently reduce flow-mediated dilation (FMD) in young adults. The impact of aging on the contribution of NO and PG to FMD is unknown. Methods. FMD was measured in older adults (n = 10, 65 ± 3 y) after arterial infusion of saline, N(G)-monomethyl-L-arginine (L-NMMA), and ketorolac + L-NMMA. Data were compared to published data in young adults. Results. L-NMMA reduced FMD in older adults (8.9 ± 3.6 to 5.9 ± 3.7%) although this was not statistically significant (P = 0.08) and did not differ (P = 0.74) from the reduction observed in young adults (10.0 ± 3.8 to 7.6 ± 4.7%; P = 0.03). Blocking PN did not affect FMD in young or older adults. In older adults, L-NMMA reduced (n = 6; range = 36-123% decrease), augmented (n = 3; 10-122% increase), or did not change FMD (n = 1; 0.4% increase). After PN blockade, FMD responses were reduced (n = 2), augmented (n = 6), or unaffected (n = 1). Conclusions. NO or PN blockade did not consistently reduce FMD in healthy older adults, suggesting the existence of redundant vasodilator phenotypes as observed previously in young adults.
背景。阻断一氧化氮（NO）和血管舒张性前列腺素（PN）并不能始终如一地降低年轻人的血流介导的血管舒张（FMD）。衰老对NO和PG在FMD中所起作用的影响尚不清楚。方法。在老年受试者（n = 10，65±3岁）中，经动脉输注生理盐水、N(G)-单甲基-L-精氨酸（L-NMMA）以及酮咯酸+L-NMMA后测量FMD。将数据与已发表的年轻人数据进行比较。结果。L-NMMA降低了老年受试者的FMD（从8.9±3.6%降至5.9±3.7%），尽管这在统计学上不显著（P = 0.08），且与在年轻人中观察到的降低情况（从10.0±3.8%降至7.6±4.7%；P = 0.03）相比无差异（P = 0.74）。阻断PN对年轻人或老年受试者的FMD均无影响。在老年受试者中，L-NMMA使FMD降低（n = 6；降低幅度为36 - 123%）、增加（n = 3；增加幅度为10 - 122%）或无变化（n = 1；增加0.4%）。在PN阻断后，FMD反应降低（n = 2）、增加（n = 6）或未受影响（n = 1）。结论。在健康老年受试者中，阻断NO或PN并不能始终如一地降低FMD，这表明存在如先前在年轻人中观察到的冗余血管舒张表型。
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