Evidence for two independent effects of oestradiol benzoate on the renin-angiotensin-aldosterone system

Estrogen effects on plasma volume, arterial blood pressure, interstitial space, plasma proteins, and blood viscosity in sheep

In adult castrated ewes the infusion of 17 beta-estradiol for 3 weeks was associated with a 12% increase in body weight, a 20% increase in whole blood volume (mainly due to a 27% increase of plasma volume), a 13% decrease in mean arterial blood pressure, and a 40% increase in heart rate. The change in plasma volume correlated with the change in estradiol concentration (r = 0.72). Most of the fluid was retained in the interstitial space, as represented by a 6 kg weight gain, 10% of which was in the intravascular compartment. Whole blood and plasma viscosity increased 16% and 21%, respectively, thus reversing some of the blood volume effects toward a hyperdynamic cardiovascular state. We conclude that many of the cardiovascular and hematologic changes with estrogen administration are similar to the changes observed during pregnancy, with the proposed requirement of decrease in mean arterial blood pressure as a condition for blood volume expansion.

Effect of stilboestrol on sodium balance, cardiac state, and renin-angiotensin-aldosterone activity in prostatic carcinoma

A prospective study examined the sequential effects of diethylstilboestrol (stilboestrol) on sodium balance, cardiac state, and renin-angiotensin-aldosterone activity in six patients with metastatic carcinoma of the prostate. Whereas metabolic balance studies did not show evidence of sodium retention during the first seven days of treatment, there was a significant and progressive increase in plasma volume after three months (mean increase 541 ml; p less than 0.01). Stilboestrol increased supine plasma renin and angiotensin II values but the response of renin-angiotensin-aldosterone activity to erect posture was progressively reduced during treatment. No significant changes in blood pressure or indices of cardiac function occurred during the three months of observation. The findings of increased basal renin-angiotensin-aldosterone activity and an increase in plasma volume suggest an important mechanism of the cardiac complications associated with oestrogen treatment.