Aging attenuates purinergic, but not muscarinic and nicotinic, cutaneous vasodilation in men

Abstract

Objective: We evaluated the hypothesis that aging attenuates muscarinic, nicotinic, and purinergic receptor related cutaneous vasodilation. Methods: In 11 young (24±4 years) and 11 older males (61±8 years), cutaneous vascular conductance (CVC) was assessed at three forearm skin sites that were infused with either: 1) methacholine (muscarinic receptor agonist, 5 doses: 0.0125, 0.25, 5, 100, 2000 mM), 2) nicotine (nicotinic receptor agonist, 5 doses: 1.2, 3.6, 11, 33, 100 mM), or 3) adenosine triphosphate (ATP) (purinergic receptor agonist, 5 doses: 0.03, 0.3, 3, 30, 300 mM). Each agonist was administered for 25 min per dose. Results: 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 0.3 mM) or high (300 mM) concentrations, CVC was reduced in the older relative to the young males at moderate concentrations of ATP (3mM:23±6 vs. 40±13%max, 30 mM:62 ± 11 vs. 83 ± 8%max, both P≤0.05). Conclusions: We show that aging attenuates purinergic, but not muscarinic or nicotinic, cutaneous vasodilation in men.