Aging in rats was associated with a 7% decrease in mean arterial pressure during orthostatic stress and diminished maximal vasoconstriction to norepinephrine in adipose resistance arteries (18% vs 42%).
Does aging affect mean arterial pressure and regional vascular conductance responses during orthostatic stress in rats?
Aging reduces the ability to maintain mean arterial pressure during orthostatic stress in rats, which is associated with diminished vasoconstriction of adipose resistance arteries.
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 degrees 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.
Ramsey et al. (Fri,) conducted a other in Orthostatic stress. Aging vs. Young rats was evaluated on Mean arterial pressure (MAP) response during 70 degrees head-up tilt and maximal vasoconstriction to norepinephrine. Aging in rats was associated with a 7% decrease in mean arterial pressure during orthostatic stress and diminished maximal vasoconstriction to norepinephrine in adipose resistance arteries (18% vs 42%).