NOS inhibition blunted the passive leg movement-induced peak increase in leg blood flow in young men (431 vs 668 Δml/min; P=0.03) but had no effect in older men (P=0.59).
Does NO synthase inhibition affect passive leg movement-induced leg blood flow differently in young versus old men?
The age-associated reduction in passive leg movement-induced leg blood flow is primarily due to a reduced contribution of nitric oxide to vasodilation.
Absolute Event Rate: 431% vs 668%
p-value: p=0.03
In young healthy men, passive leg movement (PLM) elicits a robust nitric oxide (NO)-dependent increase in leg blood flow (LBF), thus providing a novel approach to assess NO-mediated vascular function. While the magnitude of the LBF response to PLM is markedly reduced with age, the role of NO in this attenuated response in the elderly is unknown. Therefore, this study sought to determine the contribution of NO in the PLM-induced LBF with age. Fourteen male subjects (7 young, 24 ± 1 yr; and 7 old, 75 ± 3 yr) underwent PLM with and without NO synthase (NOS) inhibition achieved by intra-arterial infusion of N(G)-monomethyl-L-arginine (L-NMMA). LBF was determined second-by-second by Doppler ultrasound, and central hemodynamics were measured by finger photoplethysmography. NOS inhibition blunted the PLM-induced peak increase in LBF in the young (control: 668 ± 106; L-NMMA: 431 ± 95 Δml/min; P = 0.03) but had no effect in the old (control: 266 ± 98; L-NMMA: 251 ± 92 Δml/min; P = 0.59). Likewise, the magnitude of the reduction in the overall (i.e., area under the curve) PLM-induced LBF response to NOS inhibition was less in the old (LBF: -31 ± 18 ml) than the young (LBF: -129 ± 21 ml; P < 0.01). These findings suggest that the age-associated reduction in PLM-induced LBF in the elderly is primarily due to a reduced contribution to vasodilation from NO and therefore support the use of PLM as a novel approach to assess NO-mediated vascular function across the lifespan.
Trinity et al. (Fri,) conducted a other in Healthy (n=14). Intra-arterial infusion of N(G)-monomethyl-L-arginine (L-NMMA) vs. Control (without NOS inhibition) was evaluated on Peak increase in leg blood flow (LBF) in young men (Δml/min) (p=0.03). NOS inhibition blunted the passive leg movement-induced peak increase in leg blood flow in young men (431 vs 668 Δml/min; P=0.03) but had no effect in older men (P=0.59).