Key result
Intra-femoral artery phentolamine evoked greater increases in femoral blood flow in older compared with young men (105% vs 60%, P<0.001), eliminating age-associated baseline differences.
Why the study?
Does local alpha-adrenergic receptor blockade eliminate age-associated reductions in basal limb blood flow and vascular conductance in healthy men?
Does local alpha-adrenergic receptor blockade eliminate age-associated reductions in basal limb blood flow and vascular conductance in healthy men?
Age-related reductions in basal limb blood flow and vascular conductance in men are largely mediated by chronically elevated sympathetic alpha-adrenergic vasoconstriction.
May limit functional capacity in aging; leaves open alpha-adrenergic mediation and interventional targets.
Basal whole-limb blood flow and vascular conductance decrease with age in men. We determined whether these age-associated changes in limb haemodynamics are mediated by tonically augmented sympathetic alpha-adrenergic vasoconstriction. 2. Seven young (28 +/- 2 years; mean +/- S.E.M.) and eight older (64 +/- 2 years) healthy, normotensive adult men were studied. Baseline femoral artery blood flow (Doppler ultrasound) and calculated vascular conductance were 29 and 31 % lower, respectively, and vascular resistance was 53 % higher in the older men (all P < 0.001). 3. Local (intra-femoral artery) alpha-adrenergic receptor blockade with phentolamine evoked greater increases in femoral blood flow (105 +/- 11 vs. 60 +/- 6 %) and vascular conductance (125 +/- 13 vs. 66 +/- 7 %), and reductions in vascular resistance (55 +/- 2 vs. 39 +/- 3 %) in the experimental limb of the older compared with the young men (all P < 0.001). As a result, alpha-adrenergic receptor blockade eliminated the significance of the age-associated differences in absolute levels of femoral blood flow (500 +/- 51 vs. 551 +/- 35 ml min(-1)), vascular conductance (6.02 +/- 0.73 vs. 6.33 +/- 0.26 U), and vascular resistance (0.17 +/- 0.03 vs. 0.16 +/- 0.01 U; P = 0.4-0.8, n.s.). Femoral haemodynamics in the control limb were unaffected by phentolamine administration in the contralateral (experimental) limb. Complete alpha-adrenergic receptor blockade was demonstrated by the absence of vasoconstriction in the experimental limb in response to the cold pressor test. Local propranolol was administered to control for any beta-adrenergic effects of phentolamine. Propranolol did not affect haemodynamics in the experimental or control limbs. 4. Our results indicate that the age-related reductions in basal limb blood flow and vascular conductance are mediated largely by chronically elevated sympathetic alpha-adrenergic vasoconstriction. This may have important physiological and pathophysiological implications for the ageing human.
No takes yet. Share an insight, caveat, or question.
Dinenno et al. (2001) studied Healthy ageing (n=15). Intra-femoral artery phentolamine vs. Young men was evaluated on Increase in femoral blood flow (p=<0.001). Intra-femoral artery phentolamine evoked greater increases in femoral blood flow in older compared with young men (105% vs 60%, P<0.001), eliminating age-associated baseline differences.
Synapse has enriched 5 closely related papers on similar clinical questions. Consider them for comparative context: