Redundant vasodilator pathways underlying radial artery flow-mediated dilation are preserved in healthy aging

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. © 2014 kevin d. ballard et al.