What is the clinical evidence from this study?

Study design: Other. Population: Healthy aging (n=10). Intervention: L-NMMA and ketorolac + L-NMMA vs. Saline. Primary outcome: Flow-mediated dilation (FMD) (p=0.08).

January 1, 2014Open Access

Redundant Vasodilator Pathways Underlying Radial Artery Flow-Mediated Dilation Are Preserved in Healthy Aging

KBKevin D. BallardUniversity of Miami Health System MTMichael E. TschakovskyPreventive Cardiology AZAmanda L. ZaleskiWellesley College

Key Result

Nitric oxide blockade with L-NMMA did not significantly reduce flow-mediated dilation in healthy older adults (8.9% to 5.9%; P=0.08), suggesting redundant vasodilator pathways.

Structured PICO

Does blockade of nitric oxide and vasodilator prostanoids reduce flow-mediated dilation in healthy older adults?

Population

10 healthy older adults (mean age 65 years) undergoing arterial infusion to assess flow-mediated dilation.

Intervention

Arterial infusion of N(G)-monomethyl-L-arginine (L-NMMA) and ketorolac + L-NMMA

Comparator

Arterial infusion of saline and published data in young adults

Outcome

Flow-mediated dilation (FMD)surrogate

Nitric oxide or prostanoid blockade does not consistently reduce flow-mediated dilation in healthy older adults, indicating preserved redundant vasodilator pathways in aging.

Main Result

Absolute Event Rate: 5.9% vs 8.9%

p-value: p=0.08

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.

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