Effects of hormone replacement therapy on hemodynamic responses of postmenopausal women to passive heating

To examine the influence of chronic hormone replacement therapy (HRT) on th e central and peripheral cardiovascular responses of postmenopausal women: to direct passive heating, seven women taking estrogen replacement therapy, seven women taking estrogen and progesterone therapy, and seven women not taking HRT were passively heated with water-perfused suits to their individ ual limit of thermal tolerance. Measurements included heart rate (HR), card iac output, blood pressure, skin blood flow, splanchnic blood flow, renal b lood flow, esophageal temperature, and mean skin temperature. Cardiac outpu t was higher in women taking estrogen and progesterone therapy than. in wom en not taking HRT (7.12 +/- 0.70 vs. 5.02 +/- 0.57 l/min at the limit of th ermal tolerance, respectively; P < 0.05) because of a higher HR. However, w hen the HR data were plotted as a percentage of the maximum HR or percentag e of HR reserve, there were no differences among the three groups of women. Neither splanchnic nor renal blood flow differ-ed among the groups of wome n. These data suggest that HRT has little effect on the cardiovascular resp onses to direct passive heating.