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Effects of aging on adipose resistance artery vasoconstriction: possible implications for orthostatic blood pressure regulation

¹Department of Kinesiology, Leisure, and Sport Sciences, East Tennessee State University, Johnson City, Tennessee; ²Division of Exercise Physiology, Department of Physiology and Pharmacology, and the Center for Interdisciplinary Research in Cardiovascular Sciences, West Virginia University School of Medicine, Morgantown, West Virginia; and ³Department of Applied Physiology and Kinesiology and the Center for Exercise Science, University of Florida, Gainesville, Florida

Submitted 13 June 2007 ; accepted in final form 30 August 2007

The purpose of this investigation was to determine mean arterial pressure (MAP) and regional vascular conductance responses in young and aged Fisher-344 rats during orthostatic stress, i.e., 70° head-up tilt (HUT). Both groups demonstrated directionally different changes in MAP during HUT (young, 7% increase; aged, 7% decrease). Vascular conductance during HUT in young rats decreased in most tissues but largely remained unchanged in the aged animals. Based on the higher vascular conductance of white adipose tissue from aged rats during HUT, resistance arteries from white visceral fat were isolated and studied in vitro. There was diminished maximal vasoconstriction to phenylephrine and norepinephrine (NE: young, 42 ± 5%; old, 18 ± 6%) in adipose resistance arteries from aged rats. These results demonstrate that aging reduces the ability to maintain MAP during orthostatic stress, and this is associated with a diminished vasoconstriction of adipose resistance arteries.

orthostatic hypotension; blood flow; tilt; visceral fat