Objective: To evaluate separately the effects of estrogen and progestagen on the cardiovascular response to a standardized mental stress test.
Methods: Seven women were studied during the early follicular phase (day 1-4) of three different menstrual cycles after randomized oral administration of either 6 mg estradiol valerate or 15 mg norethisterone acetate or placebo. Heart rate and blood pressure were recorded at rest for 2 hours after administration and throughout the stress test. Forearm plethysmography was recorded at rest and during stress.
Results: Estrogen had no effect on heart rate or blood pressure at rest. After estrogen administration the increases in heart rate (delta 14 bpm/10 bpm; p < 0.01) and diastolic blood pressure (delta 14 mmHg/9 mmHg: p = 0.06) from baseline to stress were augmented compared to those observed after placebo administration. Heart rate, systolic and diastolic blood pressures reached higher levels during stress after estrogen administration compared to placebo (delta 5 bpm, and delta 7 mmHg and delta 5 mmHg respectively; p < 0.05). Estrogen administration also caused a prolongation of the diastolic blood pressure response to stress. Progestagen compared to placebo induced an increase in heart rate already at rest (delta 4 bpm; p < 0.01), and heart rate was maintained on a higher level throughout the stress test (p < 0.05). Blood pressure at rest and pressor responses to stress were not significantly changed after progestagen administration.
Conclusions: The results indicate that estrogen is responsible for the enhanced cardiovascular responses to stress, whereas progestagen provokes a parallel upward shift of basal heart rate which is independent of level of activation.