Sympathetic nervous system contributes to the age-related impairment of flow-mediated dilation of the superficial femoral artery

• Published in: American journal of physiology. Heart and circulatory physiology 2006-12, Vol.291 (6), p.H3122-H3129
• Main Authors: Thijssen, Dick H. J, de Groot, Patricia, Kooijman, Miriam, Smits, Paul, Hopman, Maria T. E
• Format: Article
• Language: English
• Subjects: Adult; Aged; Aging; Aging - physiology; Cold Temperature; Endothelium, Vascular - physiology; Exercise; Exercise - physiology; Exercise Test; Femoral Artery - innervation; Femoral Artery - physiology; Gerontology; Humans; Leg - blood supply; Male; Nervous system; Nitroglycerin - pharmacology; Pressoreceptors - physiology; Regional Blood Flow - physiology; Sympathetic Nervous System - physiology; Vasodilation - drug effects; Vasodilation - physiology; Vasodilator Agents - pharmacology; Veins & arteries
• ISSN: 0363-6135; 1522-1539
• DOI: 10.1152/ajpheart.00240.2006

1 Department of Physiology, Institute of Fundamental and Clinical Movement Sciences, and 2 Department of Pharmacology-Toxicology, Radboud University Nijmegen Medical Center, Nijmegen, The Netherlands Submitted 8 March 2006 ; accepted in final form 5 July 2006 The physiological aging process is associated with endothelial dysfunction, as assessed by flow-mediated dilation (FMD). Aging is also characterized by increased sympathetic tone. Therefore, the aim of the present study is to assess whether acute changes in sympathetic activity alter FMD in the leg. For this purpose, the FMD of the superficial femoral artery was determined in 10 healthy young (22 ± 1 yr) and 8 healthy older (69 ± 1 yr) men in three different conditions: 1 ) at baseline, 2 ) during reduction of sympathetic activity, and 3 ) during sympathetic stimulation. Reduction of sympathetic activity was achieved by performing a maximal cycling exercise, leading to postexercise attenuation of the sympathetic responsiveness in the exercised limb. A cold pressor test was used to increase sympathetic activity. Nitroglycerin (NTG) was used to assess endothelium-independent vasodilation in all three conditions. Our results showed that, in older men, the FMD and NTG responses were significantly lower compared with young men ( P = 0.001 and P = 0.02, respectively). In older men, sympathetic activity significantly affected the FMD response [repeated-measures (RM) ANOVA: P = 0.01], with a negative correlation between the level of sympathetic activity and FMD ( R = –0.41, P = 0.049). This was not the case for NTG responses (ANOVA; P = 0.48). FMD and NTG responses in young men did not differ among the three conditions (RM-ANOVA: P = 0.32 and P = 0.31, respectively). In conclusion, in older men, FMD of the femoral artery is impaired. Local attenuation of the sympathetic responsiveness partly restores the FMD in these subjects. In contrast, in young subjects, acute modulation of the sympathetic nervous system activity does not alter flow-mediated vasodilation in the leg. endothelium-dependent dilation; cold pressor test; exercise Address for reprint requests and other correspondence: M. T. E. Hopman, Dept. of Physiology, Radboud Univ. Nijmegen Medical Centre, PO Box 9101, 6500 HB Nijmegen, The Netherlands (e-mail: M.Hopman{at}fysiol.umcn.nl )