Aging attenuates adenosine triphosphate-induced, but not muscarinic and nicotinic, cutaneous vasodilation in men.

Abstract

We evaluated the hypothesis that aging attenuates muscarinic, nicotinic, and ATP-related cutaneous vasodilation. In 11 young (24±4years) and 11 older males (61±8years), CVC was assessed at 3 forearm skin sites that were infused with either: (i) methacholine (muscarinic receptor agonist, 5 doses: 0.0125, 0.25, 5, 100, 2000mmol/L), (ii) nicotine (nicotinic receptor agonist, 5 doses: 1.2, 3.6, 11, 33, 100mmol/L), or (iii) ATP (purinergic receptor agonist, 5 doses: 0.03, 0.3, 3, 30, 300mmol/L). Each agonist was administered for 25minutes per dose. We showed that CVC at all doses of methacholine did not differ between groups. Similarly, no between-group differences in CVC were observed during nicotine administration at all doses administered. By contrast, while no differences in CVC were measured during the administration of ATP at low (0.03 and 0.3mmol/L) or high (300mmol/L) concentrations, CVC was reduced in the older relative to the young males at moderate concentrations of ATP (3mmol/L: 23±6 vs 40±13%max, 30mmol/L: 62±11 vs 83±8%max, both P≤.05). We show that aging attenuates ATP-induced, but not muscarinic or nicotinic, cutaneous vasodilation in men.