Context: Differences in postmenopausal endogenous sex hormone concentrations are associated with varying risk of a growing number of common diseases. The relationships between postmenopausal endogenous sex hormone concentrations and vascular function are not well understood.

Objective: We examined in postmenopausal women the relationships between endogenous sex hormone concentrations and both blood pressure (BP) and renal vascular resistance (RVR), at baseline and in response to infused angiotensin II (AngII).

Subjects, Interventions, and Main Outcome Measures: Thirty-four hypertensive, postmenopausal women were studied in low-sodium and/or high-sodium balance. Serum estradiol, serum progesterone, BP, and RVR were measured at baseline. BP and RVR were remeasured after AngII infusion.

Results: In low-sodium balance, the increases in systolic and diastolic BP in response to infused AngII were blunted with increased serum progesterone concentrations (P<0.05). The increase in RVR in response to infused AngII was also blunted with increased serum progesterone concentrations (P<0.005). The relationships between progesterone concentration and vascular response to AngII were independent of age, body mass index, and estradiol concentration. There were no significant correlations between estradiol concentration and BP or RVR response to AngII. There were no significant correlations between sex hormone concentrations and baseline BP or RVR. In high-sodium balance, there were no significant associations between sex hormone concentrations and vascular measures.

Conclusions: In postmenopausal women in low-sodium balance, the pressor and renovascular responses to AngII are blunted with increased endogenous progesterone concentrations. Our findings suggest a role for endogenous progesterone in modulating vascular function, even within the low postmenopausal range.