The effects of age and gender on brachial artery endothelium‐dependent vasoactivity are stimulus‐dependent

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Abstract
Impaired endothelium‐dependent vasomotion in response to flow‐mediated, cholinergic, and cold pressor stimulation has been demonstrated in the presence of both atherosclerosis and cardiac risk factors. This study investigated the effects of different vasoactive stimuli on brachial artery vasomotion with respect to age and gender. Forty healthy subjects (20 men and 20 women), ages 23 to 52 years, were studied. Using 7.5 MHz ultrasound, brachial artery diameter and Doppler flow velocity at baseline, following 5 min of ipsilateral blood pressure cuff occlusion (flow‐mediated), during contralateral hand immersion in ice (cold pressor) and after sublingual nitroglycerin administration, were measured in older subjects (> 40 yrs) and younger subjects (< 40 yrs). Among normal subjects, % diameter change in response to the flowmediated stimulus was less in older men than in younger men (6.8 ± 3.2% vs. 11.5 ± 7.4%, p < 0.05); older and younger women had comparable responses (10.0 ± 5.3% vs. 11.6 ± 4.3%, p = NS). With cold pressor, normal older men and older women vasoconstricted (–1.2 ± 0.9%, –2.2 ± 4.7%) compared with younger subjects who vasodilated (1.4 ± 2.5%, 0.6 ± 2.3%, p<0.02). The cold pressor test elicited comparable responses among older normal subjects. Nitroglycerin, a nonendothelium‐mediated stimulus, induced significant vasodilatation in all the groups. In conclusion, endothelium‐mediated responses in subjects of varying age and gender are stimulus‐dependent. Flow‐mediated vasodilatation could not differentiate older premenopausal women from younger women; cold pressor stimulus could.