title: Increased abdominal-to-peripheral fat distribution contributes to altered autonomic-circulatory control with human aging.
abstract: Autonomic nervous system (ANS) control of the circulation is altered with aging in adult humans. Similar changes are observed in obesity, particularly abdominal obesity. To determine whether age-associated differences in ANS-circulatory function can be partially explained by increased body fatness, we examined ANS function and three expressions of adiposity (total body fat, abdominal body fat, and abdominal-to-peripheral body fat distribution; dual-energy X-ray absorptiometry) in 43 healthy men: 27 young (25 +/- 1 yr) and 16 older (65 +/- 1). ANS functions assessed included 1) autonomic support of arterial blood pressure (BP; radial artery catheter), i.e., the reduction in BP during versus before acute ganglionic blockade (GB; intravenous trimethaphan); 2) baroreflex buffering, i.e., the increase in systolic BP with continuous incremental and bolus infusions of phenylephrine during versus before GB; 3) cardiovagal baroreflex sensitivity (Oxford technique); and 4) heart rate variability (time- and frequency-domain analyses). Covarying for abdominal-to-peripheral fat distribution reduced or abolished age-related differences in ANS support of BP, cardiovagal baroreflex sensitivity, and heart rate variability but did not affect age-related differences in baroreflex buffering. Covarying for abdominal and total fat had small selective or no effects on age-associated differences in autonomic-circulatory control. Abdominal-to-peripheral fat distribution explains a significant portion of the variance in a number of autonomic-circulatory functions attributable to aging. Therefore, the development of this fat pattern may contribute to several changes in ANS-cardiovascular function observed with aging. These results may help explain how changes in body fat distribution with advancing age are linked to impairments in circulatory control.
authors.affiliation: Dept. of Integrative Physiology, University of Colorado at Boulder, UCB 354, Boulder, CO 80309, USA. christou@colorado.edu
authors.forename: Demetra D
authors.initials: DD
authors.lastname: Christou
authors.forename: Pamela Parker
authors.initials: PP
authors.lastname: Jones
authors.forename: Annemarie E
authors.initials: AE
authors.lastname: Pimentel
authors.forename: Douglas R
authors.initials: DR
authors.lastname: Seals
mesh_terms: D000005:Abdomen; D000273:Adipose Tissue / Q000033:anatomy & histology / Q000502:physiology*; D000328:Adult; D000368:Aged; D000375:Aging / Q000502:physiology*; D001341:Autonomic Nervous System / Q000187:drug effects / Q000502:physiology*; D017704:Baroreflex / Q000187:drug effects / Q000502:physiology; D001794:Blood Pressure / Q000187:drug effects / Q000502:physiology; D001823:Body Composition; D015992:Body Mass Index; D005730:Ganglionic Blockers / Q000008:administration & dosage; D006321:Heart / Q000294:innervation / Q000502:physiology; D006339:Heart Rate / Q000187:drug effects / Q000502:physiology; D006801:Humans; D008297:Male; D008875:Middle Aged; D010656:Phenylephrine / Q000008:administration & dosage; D014294:Trimethaphan / Q000008:administration & dosage; D014630:Vagus Nerve / Q000502:physiology*; D014662:Vasoconstrictor Agents / Q000008:administration & dosage
chemical_list: D005730:Ganglionic Blockers; D014662:Vasoconstrictor Agents; D010656:Phenylephrine; D014294:Trimethaphan