Elderly women demonstrate an attenuated vasoconstrictive response during a cold pressor stimulus

Animal studies have shown that adrenergic vasoconstriction is reduced in older females but not males. The purpose of this study was to compare sympathetic and vasoconstrictor responses to a cold pressor stimulus between elderly women and men to determine whether sex differences in adrenergic vasoconstriction exist in aged humans. Heart rate (HR), arm blood pressure (systolic, SBP; diastolic, DBP) and muscle sympathetic nerve activity (MSNA) were measured in 9 women and 10 men [age: 69±7 (SD) vs. 69±4 yrs, respectively] during baseline (BL), a 2‐min cold pressor test (CPT), and 3‐min of recovery. HR during CPT (71±8 vs. 68±11 beats/min, P =NS) and changes in HR from BL (ΔHR: 4±5 vs. 4±6 beats/min, P =NS) were the same between the sexes. MSNA responses to CPT (BL: 543±289 vs. 491±145 a.u./min; CPT: 1039±567 vs. 965±161 a.u./min, both P =NS) were similar between elderly women and men; however, women did not demonstrate as large of an increase in DBP compared to men (CPT: 84±25 vs. 98±14 mmHg, P =0.02; ΔDBP: 8±10 vs. 22±12 mmHg, P =0.04). SBP was similar between the groups (BL: 129±42 vs. 129±11 mmHg; CPT: 150±46 vs. 156±19 mmHg; both P =NS). These findings suggest that elderly women demonstrate an attenuated vasoconstrictive response to a CPT when compared to elderly men. It is likely that the attenuated vasoconstrictive response in women is due to a decrease in vascular smooth muscle sensitivity to α1‐adrenergic stimulation.