Aging and aerobic fitness affect the contribution of noradrenergic sympathetic nerves to the rapid cutaneous vasodilator response to local heating

Tew, Garry, Saxton, John, Klonizakis, Markos, Moss, James, Ruddock, Alan and Hodges, Gary (2011) Aging and aerobic fitness affect the contribution of noradrenergic sympathetic nerves to the rapid cutaneous vasodilator response to local heating. Journal of Applied Physiology, 110 (5). pp. 1264-1270. ISSN 8750-7587

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Abstract

Sedentary aging results in a diminished rapid cutaneous vasodilator response to local heating. We investigated whether this diminished response was due to altered contributions of noradrenergic sympathetic nerves by assessing 1) the age-related decline and 2) the effect of aerobic fitness. Using laser-Doppler flowmetry, we measured skin blood flow (SkBF) in young (24 ± 1 yr) and older (64 ± 1 yr) endurance-trained and sedentary men (n = 7 per group) at baseline and during 35 min of local skin heating to 42°C at 1) untreated forearm sites, 2) forearm sites treated with bretylium tosylate (BT), which prevents neurotransmitter release from noradrenergic sympathetic nerves, and 3) forearm sites treated with yohimbine + propranolol (YP), which antagonizes α- and β-adrenergic receptors. SkBF was converted to cutaneous vascular conductance (CVC = SkBF/mean arterial pressure) and normalized to maximal CVC (%CVCmax) achieved by skin heating to 44°C. Pharmacological agents were administered using microdialysis. In the young trained group, the rapid vasodilator response was reduced at BT and YP sites (P < 0.05); by contrast, in the young sedentary and older trained groups, YP had no effect (P > 0.05), but BT did (P > 0.05). Neither BT nor YP affected the rapid vasodilator response in the older sedentary group (P > 0.05). These data suggest that the age-related reduction in the rapid vasodilator response is due to an impairment of sympathetic-dependent mechanisms, which can be partly attenuated with habitual aerobic exercise. Rapid vasodilation involves noradrenergic neurotransmitters in young trained men and nonadrenergic sympathetic cotransmitters (e.g., neuropeptide Y) in young sedentary and older trained men, possibly as a compensatory mechanism. Finally, in older sedentary men, the rapid vasodilation appears not to involve the sympathetic system.

Item Type:	Article
Additional Information:	PUBMED ID: 21330615
Subjects:	B100 Anatomy, Physiology and Pathology C600 Sports Science
Department:	Faculties > Health and Life Sciences > Sport, Exercise and Rehabilitation
Depositing User:	Prof Garry Tew
Date Deposited:	04 Aug 2015 15:03
Last Modified:	12 Oct 2019 15:29
URI:	http://nrl.northumbria.ac.uk/id/eprint/23504

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