Ageing augments nicotinic and adenosine triphosphate-induced, but not muscarinic, cutaneous vasodilatation in women.

Abstract

What is the central question of this study? Does ageing augment muscarinic, nicotinic and/or ATP-mediated cutaneous vasodilatation in women? What is the main finding and its importance? Ageing augments nicotinic and ATP-induced, but not muscarinic, cutaneous vasodilatation in women. This will stimulate future studies assessing the pathophysiological significance of the augmented microvascular responsiveness in older women compared to their young counterparts. We previously reported that ageing attenuates adenosine triphosphate (ATP)-induced, but not muscarinic and nicotinic, cutaneous vasodilatation in men, and that ageing may augment cutaneous vascular responses in women. In the present study, we evaluated the hypothesis that ageing augments muscarinic, nicotinic and/or ATP-mediated cutaneous vasodilatation in healthy women. In 11 young (23±5years) and 11 older (60±8years) women, cutaneous vascular conductance was evaluated at three forearm skin sites that were perfused with (1) methacholine (muscarinic receptor agonist, 5 doses: 0.0125, 0.25, 5, 100, 2000mm), (2) nicotine (nicotinic receptor agonist, 5 doses: 1.2, 3.6, 11, 33, 100mm), or (3) ATP (purinergic receptor agonist, 5 doses: 0.03, 0.3, 3, 30, 300mm). Each agonist was administered for 25min per dose. Methacholine-induced increases in cutaneous vascular conductance were not different between groups at all doses (all P>0.05). However, a nicotine-induced elevation in cutaneous vascular conductance at the lowest concentration (1.2mm) was greater in older vs. young women (43±15vs. 26±10%max, P=0.04). ATP-induced increases in cutaneous vascular conductance at moderate and high doses (3 and 30mm) were also greater in older relative to young women (3mm, 44±11vs. 28±10%max, P=0.02; 30mm, 83±14vs. 64±17%max, P=0.05). Therefore, ageing augments nicotinic and ATP-induced, but not muscarinic, cutaneous vasodilatation in women.