Attenuated peripheral vasoconstriction during an orthostatic challenge in older men

Area of Science:

• Physiology
• Gerontology
• Cardiovascular Research

Background:

• Orthostatic hypotension is prevalent in older men, increasing morbidity and mortality.
• The leg vascular bed plays a key role in blood pressure regulation during orthostatic stress.
• The specific contribution of the leg vasculature to increased peripheral resistance during orthostatic challenges is not well understood.

Purpose of the Study:

• To investigate the differences in tilt-induced peripheral vasoconstriction within the leg vascular bed between young and older men.
• To quantify the age-related changes in calf vascular resistance during orthostatic challenges.

Main Methods:

• Venous occlusion plethysmography was used to measure forearm and calf blood flow in 12 young and 12 older men.
• Participants underwent a 30-degree head-up tilt (HUT) to induce an orthostatic challenge.
• Forearm and calf vascular resistance were calculated by dividing mean arterial blood pressure by blood flow.

Main Results:

• Both young and older men exhibited increases in calf and forearm vascular resistance during HUT.
• The percentage increase in forearm vascular resistance was comparable between the two age groups.
• Older men demonstrated a significantly lower percentage increase in calf vascular resistance (96%) compared to young men (175%).

Conclusions:

• Advancing age is associated with a diminished increase in calf vascular resistance in response to tilting.
• This attenuated vasoconstriction in the leg vasculature may be a contributing factor to the development of orthostatic hypotension in older individuals.