Open AccessAge and sex differences in sympathetic and hemodynamic responses to hypoxia and cold pressor test
Author(s) -
Miller Amanda J.,
Cui Jian,
Luck J. Carter,
Sinoway Lawrence I.,
Muller Matthew D.
Publication year - 2019
Publication title -
physiological reports
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.918
H-Index - 39
ISSN - 2051-817X
DOI - 10.14814/phy2.13988
Subject(s) - cold pressor test , vasoconstriction , medicine , vasodilation , hypoxia (environmental) , blood pressure , vascular resistance , femoral artery , hemodynamics , blood flow , cardiology , heart rate , anesthesia , oxygen , chemistry , organic chemistry
Emerging evidence suggests that sympathetic vasoconstriction is lower in young women. We hypothesized that increases in muscle sympathetic nerve activity ( MSNA ) during acute physiological stressors induce less vasoconstriction in young women compared to young men. Healthy young men ( n = 10, 27 ± 1 years), young women ( n = 12, 25 ± 1 years), and older women ( n = 10, 63 ± 6 years) performed the cold pressor test (hand in ice for 2 min) and continuous hypoxia (10% O 2 , 90% N 2 ) for 5 min. MSNA , femoral blood flow velocity, heart rate, and blood pressure were acquired continuously. Femoral artery diameter was obtained every minute and used to calculate femoral blood flow, and femoral vascular resistance and conductance. MSNA responses to cold pressor test ( P = 0.345) and hypoxia ( P = 0.969) were not different between groups. Young women had greater femoral blood flow ( P = 0.002) and vascular conductance ( P = 0.041) responses to cold pressor test compared with young men. The femoral blood flow response to hypoxia was not different between the two sexes but the increase in femoral flow was attenuated in older women compared with younger women ( P = 0.036). These data show that young women had paradoxical vasodilation to cold pressor test. The mechanisms responsible for the attenuated sympathetic vasoconstriction or for enhanced vasodilation in young women during the CPT require further investigation.