Estrogen inhibition of corticoid hypertension in chickens.

Estrogens tend to lower the blood pressure of cockerels. Estrogen-treated cockerels and estro-gen-secreting hens are immune to the chronic pressor effects of desoxycorticosterone acetate (DCA) and cortisone. B OTH desoxycorticosterone acetate (DCA) and cortisone effect moderate hypertension in cockerels." 2 The present studies demonstrate that estrogen-treated cockerels and estrogen-secreting hens are immune to this corticoid-induced blood pressure elevation. METHODS The experimental designs and technics were generally in accord with the standardized procedures of the departments Four series of experiments were accomplished varying in duration from five to nine weeks and utilizing a total of 95 chickens (table 1). In three series (BC 20, BC 31A and BC 31B), cockerels were utilized, and the effects of exogenous estrogens on corticoid hypertension assessed. In one series (BC 29), mature, gonadally active, egg laying hens were utilized, to determine whether desoxycorticosterone acetate would induce increased blood pressure in the presence of endog-enous estrogen secretion. In two series (BC 29 and 31A), 1 per cent sodium chloride was incorporated in the feed, to increase the hypertensive effect of desoxycorticosterone acetate.' In two series (BC 20 and BC 31A), a cholesterol-supplemented mash was fed, since it was desired concomitantly to study atherogenesis.6 Blood pressure was determined on the unanesthe-tized quiescent bird, kept lying on its side on an animal board. A sciatic artery was isolated by blunt Ill. These studies were supported in part by the Michael Reese Research Foundation and by a grant from the National Heart Institute (H897). Some of these findings were originally presented before the American Physiological Society3 and the Second World Congress of Cardiology4. These studies were done during the tenure of a Fellowship as an Established Investigator of the American Heart Association. 896 dissection and cannulated under direct visualization with a 20 gage needle, precautions being taken to eliminate blood loss. A Lilly electromanometer and Sanborn direct-writing twin Visocardiette were used to obtain and record blood pressure. Unanesthetized birds were bled via a wing vein. The blood was immediately heparinized, centrifuged , and the plasma removed. Plasma sodium and potassium concentrations were determined with a Beckman flame photometer. RESULTS Blood Pressures. In three series of experiments with cockerels, estrogens consistently inhibited the pressor response to corticoids (table 2). Estrogens were equally effective in preventing the hypertensive action of de-soxycorticosterone acetate, desoxycorticos-terone acetate plus sodium chloride and corti-sone. Estrogen administration tended generally to induce blood pressure levels lower than controls. …