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

الملخص EN

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.