title: Redundant vasodilator pathways underlying radial artery flow-mediated dilation are preserved in healthy aging.
abstract: 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.
authors: Division of Cardiology, Hartford Hospital, 80 Seymour Street, Hartford, CT 06102, USA.
authors: Kevin D
authors: KD
authors: Ballard
authors: School of Kinesiology and Health Studies, Queen's University, 28 Division Street, Kingston, ON, Canada K7L 3N6.
authors: Michael E
authors: ME
authors: Tschakovsky
authors: Division of Cardiology, Hartford Hospital, 80 Seymour Street, Hartford, CT 06102, USA.
authors: Amanda L
authors: AL
authors: Zaleski
authors: Division of Cardiology, Hartford Hospital, 80 Seymour Street, Hartford, CT 06102, USA.
authors: Donna M
authors: DM
authors: Polk
authors: Division of Cardiology, Hartford Hospital, 80 Seymour Street, Hartford, CT 06102, USA.
authors: Paul D
authors: PD
authors: Thompson
authors: Division of Cardiology, Hartford Hospital, 80 Seymour Street, Hartford, CT 06102, USA.
authors: Francis J
authors: FJ
authors: Kiernan
authors: Division of Cardiology, Hartford Hospital, 80 Seymour Street, Hartford, CT 06102, USA ; Department of Health Sciences, University of Hartford, 200 Bloomfield Avenue, West Hartford, CT 06117, USA.
authors: Beth A
authors: BA
authors: Parker